Bamaman1 wrote:
Surge brakes work better for boats, as they're mechanical. Water and electrics don't work so well together. And a 19' boat needs brakes and tandem axles.
You're a braver man than me. I'd never consider double towing, and many states prohibit it for a reason. I'd rather rent space in a storage lot for either the boat or the RV close to where I usually camped.
A 19 ft boat could be a fishing boat with a 25 hp outboard, which may not need either! Weight is the criteria, not length.
Only saltwater is an issue for electrics because of corrosion. For freshwater electric is fine and far superior to surge, especially for mountain driving. Surge brakes overheat descending long passes. Converted mine to electric several years ago.
Some (many) brake controllers support additional axles. Just run new 10 gauge all the way back to the truck from the boat, dont tap the RV trailer brakes or you will have too much voltage drop through the factory RV brake wires.