I needed a "Note pad, pen, pencil Rifle Data Book, zeroing pages, standard data pages, shooter’s diary pages. A standard notebook will work." I went with the Rite in the Rain Dope logbook at:
https://www.riteintherain.com/no-d746-dope-logbook#D746
Jut bring a regular notebook. All that is needed. Yes, I have one of those RnR log books and never did figure out how to use the sucker for anything meaningful. You may find it useful, but I rode the short bus to school, I guess! haha But bring a plain notebook...to take, notes.
Rifle--I will have a Tikka TAC A1 with the only modification being an MDT SRS buttstock. Has a Vortex Gen 2 4.5x27. As the Tikka has a 0 MOA rail, the scope is mounted on a Badger Ordnance 20 MOA 1.54" Mount. I appear to have sufficient clearance for scope and caps.
You should be fine...you have a versatile good quality scope with a 20 MOA mount. You should have zero problem dialing out to 1K yards, right.
As for 1.54" high mount....have you put it all together yet? You have an adjustable comb (cheek piece...sigh haha) on that butt stock. Can you get it set so as to see thru the scope without occlusion when prone and in a comfortable position behind the gun?
unless there is an extra TBAC silencer, in which case I could install the 30CB brake.
Bring the CB...never can tell, right? I'm guessing since you have the CB brake that you bough a TBAC but its in jail? You probably said so but I can't remember what I had for breakfast so there is that.
Bipod--Atlas PSR BT 46 with ADM adapter and Hawk Hill Custom Talon feet. Do I need the leg extensions?
Leg extensions would be helpful. The range goes well uphill from....eh, maybe 600 and up? And if you have a nice 2 foot long section of 2x10 bring it. They will have some lumber up there but I just went to Home Depot, bought a 4' length, they cut it, and I gave one to my good friend
@GBMaryland. Def comes in handy. Shooting uphill is one of the challenges at Mifflin.
Not ready to load my own so if there is different factory type ammo I should be looking at, please let me know.
If the Norma shoots well in your rifle, then no worries. Great price...may I ask, was that $21.80/box pre-COVID and pre-Biden?
Have five magazines but would appreciate advice on storage for the rest. Was just going to bring factory boxes, as I typically do but should I bring plastic ammo case, sammo cards, or something like the TAB ammo binder or the X-Ring B.A.D.M.F?
I've just brought factory boxes. I do have a couple of ammo binders but I didn't find them any easier or faster to use than factory boxes. Not sure what they mean by broken down...perhaps referencing people who show up with a bucket of reloads????
Two mags (and perhaps an extra in case of failure) will do you.
"Shooting pad - with forward straps for bipod." Went with the TAB Pollock.
Does it have a strap of some sort in the front that load your bipod against (take out the slack, if you will). Can't tell from the picture on TAB's site.
Rear bag--Assuming USPS does not mess it up will have an Answer and Compromise
Smart man! hahaha
And you have plenty of time to get it right even if USPS screws you. I have lots of bags, even some that I like that aren't the Answer. But the Answer works very well and Marc is twice my size so I that's what I use at the clinic (haha..joking).
Tripod--Will I need one? If so, any recommendations?
Not sure what they will want to do in the 3 day format. When we went to the 2-day clinic two years ago, we didn't shoot off of a tripod. Well, Frank had his RRS set up and he provided some people who were interested the chance to shoot off of it with a bit of instruction. Last year, with combine PR1/PR2 4-day clinic, we did shoot off of tripods.
If you don't have one and don't feel like spending the $$ for a decent tripod and ball head (and it can be a sizable chunk of $$), then I'm sure people will let you use theirs.
If you absolutely want to buy a tripod, then...well, I have a Two Vets and like it a lot. RRS is the gold standard but they are also gold standard cost. Others will chip in with what they think is the best brand or best value or...whatever. Seems like there is a thread about tripods almost every week and people's recommendations are broad and varied
Depends on what you plan to do with it. I don't compete in rifles (and no longer do in skeet) so for me a tripod is not an often used bit of kit and I mostly use it for mounting observation devices (spotting scope and LRF) and a bit of deer hunting from ground blind.
Now here is a bit of a key...do you have a long ARCA or pic rail on the bottom of your fore end? You must have something at the front of it to attach a bipod but that's not where you want to attach to a tripod. Typically, you would clip into a ball head just fore of the mag well where the gun will be fairly well balanced.
No worries, however, as you can always flop a bag over a ball head and lay your gun on that. Last year I tried both. I think I was better clipped in but in PRS, many (most??) guys have a tac table on their tripod and throw a bag on it. Faster on and off, maybe? Faster panning from from one target to another, maybe? I'm 70 and don't shoot PRS and never will at this rate.
"Data Book, with writing instrument. Can just be a note pad"--see questions about Rite in Rain above.
See answer above about RnR (haha)
Range Bag holding all of the day’s shooting essentials--Went with Eberlestock G3 Phantom.
Wow, that's a lot of back pack. Very nice. I have an Eberlestock X41 HiSpeed II which suits my needs for the present. Please keep in mind that our cars will be parked right behind the firing line so you don't need to pack in every fucking thing on your back....right?
"SCOPE TOOLS--have both Borka and Fix-it kits"
Good. Whatever you might need and not have...someone up there will.
Of course eyes and ears...well, ears for sure. I personally always wear eyes when shooting.
Bring a small cooler to keep in your car with soft drinks...I suggest water for the most part. Also, there is a Wegman's 1.5 miles down the road from the hotel. Great place to buy pre-made lunches from salads to subs to poke bowls and pretty much everything in between. So, you will want to keep your lunch cool too.
I'm sure others may have some different views...and will chip in. And, if you have any further questions, bring them here and someone will surely step up to answer.
Now, its beddy by time. I leave for Georgia and quail hunting in the early morning. Now THAT is fun shooting...and great eating
Cheers
stay away 
turrets appropriately, continue on.