If you have a kill switch, you can wire the controller behind that switch, so if you want to remove your batteries, you simply use that switch and you can safely remove the batteries and keep using everything inside on solar power. (if it's not dark of course) Or on shore power for that matter.
If you need to work on 12V electric parts behind the kill switch, use the kill switch to remove battery power, remove shore power and remove power from solar. You have a few options on how to do that.
1. If you have a fuse between controller and 12V system or between controller and panel, you can remove this.
2. Install a switch on the panel.
3. Cover the panel with something that's not going to blow away by the wind.
4. Work at night, like somebody said. :B
Wiring behind the kill switch has another advantage. If you keep your camper indoors during storage or if it's always shaded or covered by snow, you can/should use the kill switch if you don't keep the RV on shore power. The controller will use battery power if the panels don't produce anything. I'm not sure if all of them do, but mine certainly does!