Please review the following:
The first two units are from the same manufacturer, but significant price differences (both show retail). Is one of them just overkill?
This next one is quite popular, and sold at Camping World and several other RV stores.
50 Amp Portable RV Surge Guard - 34750
Given the purpose is to protect your RV, and not just driven by cost, which unit (or is there yet another) would you suggest.