There are a number of appliances that can cause a GFCI to trip. While the converter is one of them, it can also be the refrigerator
120V electric heater element, or the same if you have an electric option on the hot water heater, even something as simple a a bit of water in a receptacle.
I'd try shutting off all the breakers first. If it doesn't trip, turn them on one at a time to find which is causing the problem.
If the GFCI trips with the breakers off, the problem is a neutral/ground fault, harder to find. To find a neutral/ground fault you need to disconnect the neutral of each circuit to test it. Some appliances can be unplugged which, of course disconnects the neutral, but others require digging into your breaker panel to remove the neutral wire from the neutral buss. This may be well beyond the amount of digging you want to do if you are "electrically challenged", but it is the only way to identify a fault between the neutral & ground. Rather than repeat the entire post here, I wrote one for troubleshooting GFCIs at the RV.net forum