Where can I save a few bucks without putting myself in danger?

Look really carefully at the Victron Smartshunt or BMV712- the battery monitor will let you know how full or empty the battery is. - vital to know in an RV.

va3atr, I don't know how, but I completely missed your mobile application when I sent the post above regarding my experience with Schneider/Xantrex. As many others have said, Victron is the way to go mobile, in my opinion. They have a lot of experience in marine and van applications. I built a van last year and used all Victron components - no problems as of yet, and I love their Touch 50 display and remote control panel. If interested, here is a link to the build, including the Victron install: https://sprinter-source.com/forums/index.php?threads/106963/

Just spend some time reading through the threads in this forum. You can build a very budget friendly system. As long as you choose equipment that members are using. You can get lots of help when you're ready to design your system.