You didn't ask, but here's some more stuff. You will almost certainly need the carbs cleaned. Ethanol will gum up carbs. If your trailer hasn't moved in that long, unless you have trailer tires on the trailer (instead of just car tires), you'll probably need new tires. Car tires aren't meant to sit in one spot for extended periods of time under load. Blowouts can occur, and they always occur at the worst time (as if there's a good time). You'll want to make sure the water pump impeller is working (look for a strong, steady stream of water from the motor's "pee" hole). Test the batteries. They may be shot.

If it was stored outside, uncovered (or even covered), you may find some deck rot.

As far as the 12/24 trolling system and where to put the charger, put it close to the batteries. The 12v that runs the big motor and electronics is charged by the big motor. Always carry a wrench on the boat that fits the battery terminals (make sure it fits all of them, some may have a different size). Make sure you can replace the engine battery with a trolling motor battery if you have to. While I've never run out of juice on the lake, it only needs to happen once. Trolling back to the boat ramp (in my case a spun prop) is truly the "walk of shame".