First a good place to start for understanding RV systems can be found in these links.The 12volt Side of Life (Part 1 )
; The 12volt Side of Life (Part 2 )
A good start would be a Battery to Battery charger instead of a separator/isolator, my current recommendation would be the:
KISAE DMT1230 Abso 30A DC-DC Battery Charger
or KISAE DMT1250 Abso 50A DC-DC Battery Charger
These are both battery to battery chargers with a built in solar controller. The difference between the two is $100.00 ($249.00 to $349.00) . The 50 amp version would give you more options if you're rig is capable. The goal is to match alternator and what the size of your house battery bank is. These an additional temperature sensor
and match up well to the Transit CCP point.
This would take the place of an isolator/separator, it would bring a 3 stage charger, and a solar controller. As you're roof would taken up by your toys, a portable panel setup would work great. Member Twoxentrix posted this link in another thread : Lensun 100W 160W 200W 12V Portable Folding ETFE Solar Panel for Camping Van, RVs
This does not provide emergency jump start option as a Blue Sea 7622 would provide, but I haven't used that option my rig in 15 years.
For plug in power would recommend
KISAE AC1240 Abso 40A, 12V Battery Charger
or KISAE AC1260 Abso 60A, 12V Battery Charger
Again the larger unit gives you mare capability to match the charge rate to you battery bank size. Both units support a temperature sensor
, for charger accuracy, and can charge a secondary battery bank such as your starter while plugged in.
And last I would recommend a good battery monitor:
Again my current recommendation would be the:
Balmar SG200 battery monitor
This battery monitor provides the most accurate and simplest SOC monitor, while also provide current usage data. The amp counting capabilities will allow you to better understand your daily current usage.
Without knowing your AC needs it would be hard to offer up an inverter option. I generally would think that a small 12 volt footprint would mean a small AC footprint, something in the 400 to 600 watt rage might work out out.
Pair the above units with an AGM battery and you start your minimalist setup. The battery monitor will allow you to collect data, and see if you need a larger battery bank in the future.