Cowgirl
Correct me if I'm wrong
Right now you plug the fridge into a socket/ cord powered by the inverter
When you reach the show/fairgrounds you move the fridge plug to another OUTLET for the shore power
Assuming both are located near the fridge, you simply plug the fridge into the transfer switch output, and plug the two inputs into the two power sources
One into shore outlet one into inverter power
One input is default "inverter" the other is the "switched" shore power
It switched automatically when you plug in the trailers shore chord