"My issue is whenever plugged into shore power and starting the reefer, the gfci pops and all power is shut down"
You make it sound like you have a 120 volt refrigerator. The freon type, with motor and compressor.
My advice is to go back to the top and point by point either determine if an error exists and if it does, go to the next point. Gas refrigerators do not cause a ground fault UNLESS something in the 120 vac has gone wacky. Like the heating element.
TRY plugging in with the AC plug on the refrigerator yanked. Does the GCFI trip? Then plug the refrigerator in. Did it pop the GCFI?
