It's not wise at all. Your lights operate off the 12V system, regardless if they work when plugged into the 120V AC. You need to remove those burnt and inoperative wires, install, a fuse or circuit breaker near the battery, and rewire the trailer up to the distribution panel. You need operating battery connections and an operable 12V system to move the trailer. Without 12V, you have no operating emergency break away system.
To someone unfamiliar with RV wiring or wiring in general, this may all seem like an insurmountable task but it's not. If you don't want to pay an RV specialist to do the work, start asking around to find a person conversant with electrical systems. You should be able to find a friend or a friend of a friend to help you out with this. If you decide to reconnect the batteries with the known, burnt wiring, there is a real chance that you will start a fire and possibly burn your RV to the ground.
I'm sorry, but there's no real NICE way to advise you on this, you need to fix your wiring issues. It's not that big of a job.
Maybe, if you listed your location, one of the guys on here would offer to help.
