We've been mostly off-grid campers, always. There was never a time when we were FHU glampers. So my suggestions come from that perspective.
The two most important things we did to our first trailer, was to install a pair of golf cart deep cycle batteries, and to install LED lights in all of the often used fixtures.
We went with a pair of 6v batteries, but they don't have to be. The important thing, if you want them to have a long life, is to get true deep cycle batteries. Most commonly those will be 6v. We've got a pair of Interstate that are about 10 years old. We moved them from our old trailer to our new fiver. I learned how to take care of them. And, no offense, but charging every 2-3 days is not how you take care of batteries.
The LED is the next step. But it takes some homework too. Some of it is personal taste in lighting. Some are too blue. Some are too harsh. Some create interference with other electronics. Some are not forgiving of voltage variations. You need to try some and see what suits you. Fortunately they are very inexpensive these days. My preference is for flat board with at least 36 chips. I've never liked any of the LED that are shaped like the bulbs they replace. Not enough output, and not directed where needed.
Get a good quiet generator. Use it. Everyday. Try to replace the amps you've used every single day. You cannot do it with a generator, but keep that as your goal anyway. About 2 hours at a time is the best use of the generator. If you can do that 2 hours x twice a day, even better. At the end of 2 hours your batteries will only accept a trickle, and best to shut down and let them rest.
To avoid this getting too long, I'll just let that advice sit here. There is a lot more to it, but most of it is best learned by doing. The advice from Time2Roll is excellent. Get out there doing it and learning.