RE: Sig 1/6th J3 Cub
I've got a Saito .30 w/Zinger 12/4 on mine and it is just the right power. Started with a Fox .35. Your story might inspire me to put some floats on the 1/6 Cub.
I'm kinda envious of the weight of yours. Mine is about 4 1/4 lbs. with micro servos and pull-pull on rudder and elevator.
Has a very light wing loading though. Using opposite aileron and a lot of up elevator, it will do a flat turn with the rudder in about the radius of it's wingspan (or so it looks). To me it's a very spectacular manuever.
It's covered in yellow Solartex. After five years, it's gotten pretty dirty. It looks like a dirty old Cub in need of new paint and fabric!