If it were me, I'd put the TT 61 on the high-wing trainer and put floats on it. It's a bit more power than you need, but when it comes to float flying, having extra power is a good thing.

As long as the plane and floats are set up properly, it's not too much more difficult. The main thing is to have floats that are aproximately 75% of the Fuse length (from Firewall to to rear of fuse) and have the step at or 1/2" behind the CG - also, don't forget to re-balance once you add the floats, any weight needed should be added to the floats so that when you take them off, you don't need to re-balance when you put the wheels back on.

The biggest differences are that you need to keep the wings level during takeoff and landing so you're not digging one float deeper into the water than the other float. In the air, you'll feel the extra drag, so the plane will be a little sluggish, so keep plenty of altitude if you want to try a loop or roll.