Well, I repurposed the pair of 200 amp hour LiFePo4 batteries, for a single 400 amp hour unit. Saves a mess of space that I needed to install the heater, plus I really didn't want to mount the batteries under the van in a custom built battery box...
So for starters. I have a Chins 400 amp hour smart bluetooth LiFePo4 battery. Got all the features I could want. It is scary how close in size it is to the 200 amp hour batteries, yet how much heavier it is.
Per Sportsmobile I pulled out the original AC to DC converter charger and installed a Powermax PM3-45, same rating as the original but LiFePo4 compatible. Sadly the first one is defective, waiting for delivery of the warranty replacement. Wish me luck.
I did install some extra USB power ports through the van, since that wasn't a thing in 1993. I have a few more 12v sockets to install as well.
Now that I have ONE big battery in there instead of two, I can go ahead and start my Velit gasoline heater install... Sadly this winter hasn't really been leaving me needing any heat at all. I need to head north to enjoy that luxury...