Go into the breaker box in the camper and turn off the breaker that powers the converter/charger. Then plug the camper into the house GFCI and see if it trips. If it doesn't trip, then you have a problem with that circuit in the camper, and it's likely the converter/charger since you recently changed that component. Either it's defective or you wired something wrong.
If it still trips, then turn all the breakers off in the camper, then plug in again. If it still trips then the problem is likely the cord or plug, if not, turn breakers on one at a time until the GFCI trips, and your problem will be on that circuit.