Norm,
Sorry, not really a background in electricity. Mostly reading this forum and maybe a little from a long ago ham radio hobby. I only know about the WFCO 8725 converter. The top part comes off with three screws and the AC wires can go in and out through holes in the sides. There are slots for two circuit breakers and connectors for the AC circuits.
I used a 30A power cord and inlet, but 20A might be enough. If 30A split into two circuits with a GFCI on each and then enter the converter with a 20A circuit breaker on each line inside the converter. One of the lines powers the converter itself. It draws about 4A max. For air conditioning I would go with the 30A power cord. Then if you want to take along a microwave oven too it will not be a problem.
The converter has three DC output circuits plus the battery charging circuit. The trailer battery and tow vehicle battery can both be connected to the charge circuit if desired for charging the trailer battery while towing.
The built-in fuse panel in the converter holds a fuse for each of the three DC circuits, I used 15A for those. There is also a reverse polarity fuse and another for battery charging. I used 30A fuses on those. Sorry my general knowledge is not very great and I can only describe my own setup. But it seems to work well and I am happy with this arrangement.
Bill