Why not another SA-08 in 12ga? That would make cleaning easier and when your boy grows give him the 12ga and order you a stock and take his 20ga. Trust me, 20s are the cats meow!
Bingo!
The Weatherbys are very light shotguns, so the recoil if using "heavy" duck loads might be more than you need, but only if you are going to blaze away heavily.
