I am looking for a good way to provide water resistance to the ESC and Rx in my BEAVER on floats. Any proven ideas?

Search the threads for CorrosionX
http://www.corrosionx.com/

Take a look on youtube they will show you how.

In my boating days we enclosed the receiver in a balloon or a condom and coated the exit area of the leads and antenna with silicon sealer and wrapped tightly with a rubber band. It was as water resistant as any other method at the time .