Thinking about a new solar setup for my 5th wheel

500w sounds about right. 2 245w or so panels and an MPPT controller sized to handle at least 500w.

Since your big desire is to run the fridge buying a kilowatt meter from Lowes and reading what you really use per day would be most of your energy audit to verify these estimates.

I think you are talking 6 or more batteries but knowing your usage for the fridge would give a better idea.

Camping in sunny Texas or elsewhere?

Jim