There is a way to accomplish what you are needing to do. But the 7-way isn't going to play a role in charging your battery and doesn't care if the battery is lithium or not. The hot wire coming from your 7-way would only ever be enough to trickle charge your battery.
If you are wanting to charge your battery while under way you will need a DC-DC charger like the Redarc In-Vehicle BCDC Battery Charger # 331-BCDC1225D.
You would also want a battery isolator like the Redarc Smart Start Battery... view full answer...
For a torsion axle such as your Avan Aliner we have kits available that will give you some extra clearance.
The Avan Aliner is a single axle trailer, so we have two kits that will work for you. Torsion axles must be side-mounted and not top mounted and can not be used with Torflex axles with 3 inch high profiles.
The first one I recommend is The Torflex Lift Kit - Single Axle - 2-5/8 inch Lift # K71-707-01 which is compatible with #10 Torflex axles with 2,300 to 4,000 pound capacities.... view full answer...
We do not carry the WFCO-8735-LiS, however I do have another alternative.
Instead, I recommend going with the Progressive Dynamics RV Power Control Center with AC/DC Panel and Converter/Smart Charger # PD4135K.
This is designed to replace your WFCO-8735-P, and is compatible with lithium batteries. view full answer...
The Fan-Tastic Vent 7350 Series Upgrade Kit - High/Low Style Base - White # FV807359 you asked from will allow you to use a ceiling garnish in the depth you desire on the bottom but the top will not require any changes at all..
We have the 6 inch ceiling garnish in white # FVK1060-81 or off-white # FVK1060-80 which can be cut down. The Garnish for Fan-Tastic Vents Roof Vent - 4-1/2" Leg - 14-1/4" x 14-1/4" - Off White # FVK2040-80 is also an option. I've linked the page to all the... view full answer...