The battery is really the big thing in tech that has advanced. Yes, a little risky to mount lithium in camper cause you fear it will catch fire.
Check out this full-timer's review of a couple of systems. He has a Jackery, which is a self contained power pack. A battery, controller and a small inverter in a box not much bigger than your existing battery, and it is lighter. It is portable, so you can take it out and use it, or store it wherever you want.
Down2Mob videosIf I was going to start from scratch I would consider this. The battery being a huge advantage in that it is light and you can discharge it a lot deeper than a GC battery and not damage it. Being able to discharge it deeper means you get more battery availability, so that one is now equal to two lead acid batts.