Where are you moving to in CT?
There aren't many outdoor ranges past 200 or 300 yards let alone ELR spots.
My dad and I go to Wooster Mountain in Danbury but I think thats like 50 or 75 yards and it's close to his house.
Shooting on your own land, depending on where, is legal. We have a cottage in North Stonington on 5 acres, and it's legal to shoot there, when my mom is ok with the noise lol.
I think if you build an AOW lower, you could have that in CT, so that might be a way to have your 300 BO. At least that was the case a few years back.
CT may have stopped transferring pre-ban lowers, but that's another route to check.
If you live near the NY border, be careful about having guns in the car and crossing over which is very easy, as NY likes to arrest people with guns in the car.
Scott