In my current TD, I along ago removed the battery and switched to using the 12V power outlet from a battery jumper unit like the one in the picture. I use a male/male cord into a female outlet on the trailer that taps right into my basic 12V system. I only power a couple of lights and a fan. The jumper can be charged via the cig lighter in the tow vehicle during day trips, but usually lasts a few days without any issue. It can even jump a car in a pinch. When not camping, I keep it charging on my workbench at home. My jumper is old and I have no idea what the ratings are on it.
In my remodel, I really want to avoid a traditional car battery. They are heavy, potentially dangerous, and way overkill for my needs. I don't see my total daily AH exceeding 20.
Benefits:
1. Portable
2. Can use it for other things
3. Can be charged and moved to tow vehicle
4. Can be charged/run with 110V if available, serving as a power adapter.
5. Some include air compressor
Cons:
1. Lower AH
2. Prone to theft
3. Bulky
I would appreciate any insights or opinions on this approach. If somebody has an idea what the AH is on an upper-end unit that would be great too.