I have an actual KAC/LMT SOPMOD stock assy., the whole thing including buffer, tube, etc. for sale on here. Those have a solid cheekweld and they don't wiggle like other adj. stocks do, they fit tight. SR25's and the new M110's come with these now (well, the M110 uses a Magpul version but I prefer the SOPMOD). It worked so well I built a couple rifles using SOPMODS instead of fixed stocks and have no problems. Solid cheekwelds, amazing for a collapsible stock. I use B5's too and some fit just as tight as the LMT.
There used to be cheek risers that allowed for a charging handle, they made 'em for fixed and collapsible stocks, but they were pretty tall and extended up and over to allow the charging handle to move underneath. It was cheap and it didn't work worth a damn.
In the army we'd just tape foam sleeping pad material onto the stock but depending on how you do it you may have to get creative with allowing for the charging handle or otherwise make a compromise here or there. That's gonna be your cheapest route and 100MPH tape (not the 90MPH shit) is what you want, and the pads can be found at most surplus stores cheap. You'll even have enough left over to use for a shooting mat.
I'm considering having a leather one made that laces up if I can figure out a good fit and design (damn charging handle again). It's for another KAC adj. stock but that's basically an A1 with an adj. buttplate.
There are also competition type, fully adjustable skeleton style stocks that will definitely do the job. I'd love one but they ain't cheap.