I assume that in the Cayman Islands you will be flying from salt water. Be completely fastidious with waterproofing and corrosion protection. Gasket the wing saddle, Electrics in a baggie/Balloon/condom. Especially the servo in the float. Mount the switch internally and actuate it with a pushrod. Mount all the electronic components off the floor so if any water gets in it can slosh around without soaking into somethng vital. There is an effective product called corrosionX you should spray on your electrical connectors and use as an after-run in/on your motor. CorrosionX is probably available from marine supply establishments. Rinse your airplane with fresh water after flying, then wipe it down and spray it with rubbung alcohol and wipe THAT down. Watch your clevises...they are usually carbon steel and will really rust quickly. Use plastic (EZ) hinges. Not metal hinges or even hinges with metal pins.