Put an extra piece of ply on the inside of the fuse evan with the T.E. add so triangle to make it good and strong and then get an extra set of the tall landing gear(use the tall one up front too) attach them with two nylon 1/4-20 bolts and instal Gee Bee floats onto the two sets of gear, when you want to fly on wheels remove the back landing gear and put the bolts back in to keep oily crap out of your fuselage. Use good water resistant servos on your ailerons to keep the water out...seal every opening you can and have fun...