Hello John, I would just echo what Jeff said and comment that I also installed a WFCO from Best Converter. At the time the output was 25A but I believe now the 30A unit is more or less the basic standard. Mine has worked very well and when I called Best Converter about the installation they were very helpful.
My unit draws only about 4A A/C at max output because of the difference between 12V and 120V Amps. (Amps = Watts/Volts)
The built-in fuse and CB panels are very nice and save money over installing them separately. On my converter there was space for two circuit breakers and bus bars inside the unit for A/C connections. I installed a 30A shore power inlet into my electrical compartment and then split into two 20A A/C circuits at the converter with two 20A breakers. This saves money because all the 20A outlets, switches, wire and GFCI's can be purchased at Home Depot or Lowes. The converter itself I powered with one of the 20A circuits and the same circuit goes to one of the two A/C lines into the trailer.
On the D/C side there were slots for a master fuse and three circuits below that. I used 10A fuses on the three separate circuits and 30A on the master. The master circuit is designated for charging the trailer battery and it passes battery power through to the three trailer D/C circuits if there is no A/C hookup.
I hope this description of the wiring arrangement that has worked for me will give you a starting point. I believe you will be happy with your new converter and the supplier.
The photo below shows my CB and fuse panel in the converter. Although the converter is designed to mount in a panel opening I built a small frame for it to sit in my electrical compartment. Shore power enters through the black cable (#10 wire) and exits with the two yellow #12 wires.