It is an airplane that you forgot to put wings on :-)

There are a couple of things you could do to stop the lean in turn.

Lower the CG. I would go with 3 or 4 blade props and lower the CG that way. The prop efficiency would go down a little but the lack of lean in high speed turns would be much better.
Little stub wings on either side of the outer sides of the fuse that would deflect at high speeds to keep the fuselage level would help also.

For low speed turning you might mix in throttle control with rudder to get variable thrust.

I have to comment about the lake, the water looks crystal clear, beautiful. If I had access to it Iwould have a lot of floaters also. I guess living in Canada has it's benefits.

I am accoustomed to looking at the Missouri and Mississippi Rivers as I drive over them. One inch visibility on a good day and I really wouldn't want to put a finger in either of them.