Re: getting power to electric winch
I have several of those booster packs around the shop, the newest being a Snap On YA1212A. I have three trailers with electric winches, all are Power Winch brand winches, all are roller trailers. The booster pack will power the smallest winch only, the larger two will run but won't pull any load when on the booster pack. It may work better if just loading a floating boat but I don't think I'd chance it as my only power source. I tried once to use the larger winch to load a boat which was sitting on another roller trailer, pretty much just rolling from one trailer to another, it got the boat about 1/4 of the way and died, popping the internal circuit breaker. The wires were too hot to touch. I finally just pulled the yard truck up to the winch and use a set of jumper cables and all was fine. The batteries in those booster packs are not much more than a breakaway battery or large alarm back up battery. They are fine for quick shots of power but not much good for long term power supply.
The battery on the tongue is the better idea as it puts maximum amperage near the winch. Just so it stays charged or is charged by the tow vehicle.
My main two trucks have huge jump start terminals added under the rear bumper, this gives me near full battery power to the rear of the truck. They are wired with 4/0 welding leads directly to the battery. One came with this set up, the other I added. Its extreme overkill but I had the wire and it cost me nothing but some time to do. Adding such wiring also needs to be done correctly in that a short in these wires would no doubt result in a fire. Such wires need to be protected and routed well away from moving parts and exhaust and clear of any jacking points.
There's a big span in motor sizes when it comes to winches, most smaller winches use what amounts to no more than a power window motor while others are more like a starter motor. My smaller Power Winch has a motor which is only about 3.5" in diameter and about 4" long, the largest winch looks to use a motor which looks about like an older Ford starter motor about 5" in diameter and about 10" long. The scary part is that both came with the same wiring kit and plug, only about #8 gauge wire. I replaced the two larger motor's power leads with heavier wire several years ago.