https://www.amazon.com/dp/B000HI5WTY/?tag=skimlinks_replacement-20
not sure if you could get enough depth from bit , might cut u bolt flush and drill hole for guide pin of circle cutter for each hole
I believe 1/4 will be fine , my upscale 4" mosquito is 1/4 ply several flights
last spring I flew in some wind , the wind dragged the rocket across field seemed like quarter mile no issue with fins
My wife hit a deer yesterday, but saved State Farm 10k when she did it , she was driving our totaled car from her last deer hit that I hadn't repaired yet
Rocket hauler Enclave was setting in the driveway
I have lost my onsite vendor RAH , online I buy from Chris Rocketry supply's he is the one that got me hooked on the 38/480 Case and loads
I got in for loads that don't have hazmat and like caffeine got addicted