For my connections between different model sections I use these waterproof connections in the first pic. I have five pairs of these to attend to. I use 2, 3 and 4 pin versions.
For the beacon LED to Beetle connection I use some PCB connections I strip from things that are getting thrown out. They are of course not waterproof so before each mission I dab Corrosion-X on it.
For the deck LED, I use this guy and do the same with Corrosion-X. If it comes down to it after time, they can get replaced.
Any exposed to water soldered connections, I smother with silicon then heat shrink it, then finger dab silicone on the ends of the heat shrink to make sure it is sealed.
That should answer more than what you asked Tom. For the benefit of all I guess.
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