The batteries wouldn't fit on the tongue, so I ended up installing the GC2s length-wise in a Century Plastics battery box inside the front storage area:
https://www.allbatterysalesandservic...cfm/4,576.html
What's nice about this is it's the closest I can get the batteries to the existing tongue-mounted 12v battery, thus shortening the cable run as I just bored a hold in the floor of the storage area. I vented the box to the outside and ran 2/0 AWG welding cable from the batteries to my converter to limit voltage drop, then I replaced the original converter with a PD-4655 three-stage converter. I installed a switch so I can choose whether to run/charge either or both batteries and breakers close in the positive cable of each battery replaced the crappy in-line blade fuses.
Once that was all up and running, I installed a 1,000W pure since wave inverter and wrestled for about a week over how to wire it up. I ended up speaking to Progressive Dynamics who were ridiculously helpful and the easiest, cheapest and safest thing to do was install a sub-panel to power the receptacles (all I wanted the inverter for was to charge laptops, phones, the TV and kitchen appliances) and avoid the situation where the inverted energizes the converter and gets in a nasty battery-draining feedback loop. I added in a Progressive Dynamics auto-transfer switch which automatically switches the power between shore power and inverter power.
I bought a Xantrex pure sine wave inverter as it has great reviews everywhere I looked and, having installed it and used it for a while, it’s super quiet and does the job. Time will tell if it’ll last but I’m really not pushing it. I also installed the remote switch for it so I can turn it on and off from inside the RV. Oh, and I wanted to avoid installing it in with the batteries so I put it in the closet immediately above the GC2 batteries so the cable run was nice and short but it’s in a different airspace to the batteries. It called for a bonded ground so I ran that too.
Everything works great which is nice

I tend to leave the inverter on all the time unless we’re out and with the furnace running all night (thermostat set to 68F) we’ve done three nights boondocking running pretty much everything normally and the batteries haven’t needed charging which is great cos I don’t really like running the generator when there are tenters around (I think we’ve all been there and it’s annoying). It was cool being able to pick up an LTE phone signal, tether my smart TV to it then watch Netflix in HD powered off the inverter. The wife wasn’t that impressed, but I don’t blame her, it’s pretty geeky lol!
The next thing I’ll do is get two or three 100W flexible solar panels and an MPPT charger so we can go for even longer between generator charges. I have plenty of roof space on the FF so I think I could put three panels up there. I know flexible panels have their limitations, but I really don’t want to add 50+ pounds per panel going the rigid route.
Cheers
Simon
EDIT: Man I can never get image to post on this forum grrrr! Here are the links to the pictures of the finished installation:
Imgur: The most awesome images on the Internet
Imgur: The most awesome images on the Internet
Imgur: The most awesome images on the Internet
Imgur: The most awesome images on the Internet
Imgur: The most awesome images on the Internet
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