Since you have a 2014 Big Sky I am assuming you have hydraulic jacks. There are a number of potential issues here.
1. Crushing the junction box - Was this repaired completely? There is a live 12V circuit in that box that could be affecting other electrical systems.
2. There is always constant power to the hydraulic landing jacks and slide. The only way to turn the power off is to disconnect from shore power and remove a battery cable (either the ground or positive one)
3. Having to disconnect the battery before the jacks will extend is strange. Do you have to disconnect/reconnect before retracting the jacks? How about the slides?
4. The stopping, waiting, then starting of the hydraulic motor is most likely the failure of the 50 amp self resetting circuit breaker. There is tons of dialog here on this beauty and its problems. Here is one reference.
https://www.montanaowners.com/forums...ad.php?t=78438
5. You do not have an inverter (uses12V DC to create 120V AC). You do have a converter (uses 120V AC to make 112V DC). The converter charges batteries. But it is not strong enough to run the hydraulic pump. You need a good battery to do that.