RE: Converting GP .40 Floats to Amphibious
Well, my thinking is,
With an air system you can have all the electronics, valve and servo in the plane,, just run the air lines down to the floats, just like you'll have to with those servo extensions. No electronics under the water line so if there is minor leaking (which there is sure to be) you don't fry the plane's flight system.
Same Idea with a separate flight pack,, it isolates the airplanes flight pack from the servo(s) in the float. I've seen a few guys do this in larger planes with retractable water rudders and to run the water rudder steering also.
good luck