I do not know about all RV's but my little Toyota sitting next to the house with a mostly OE system, the isolator is 100 amps continuous protected by 40 amp circuit breakers. So theoretically except for brief surges the most that can pass through there is 40 amps.
If I were in this situation I would likely flatten a piece of copper pipe and drill a couple holes. On the other hand an internet search will reveal all types of terminal extenders, expanders etc. Of course you will have to find the post size and thread size to match one up.
