Hi, Evan here.... The Outlaw on floats is mine as well as a Twin Outlaw and a Northstar and........ I like fast and I like float planes. The Shrike idea sounds absolutely fantastic!!! Yes you'll have to compensate for the rear mount engine weight but I think that by using a .25-.32 size engine and maybe making it a pusher to move the engine mass forward you shouldn't need to add additional weight to the nose other than moving everything like the battery, receiver and servos forward. Using a three bladed prop will help keep the thrust line low. You can have the servo outlets on top of the wing or use torque rods and have everything inside. Tip floats like on a Northstar WILL be needed and you might want to think of rudders and a water rudder. As far as engine thrust you'll need 3-5° of up thrust if the engines facing rearward(pusher) or down if the engine faces forward(a tractor).