Open/close to maintain 12 V battery constantly???

I have a 2005 TM 2720SL. Every time I return from camping I have to reopen my trailer and remove the 12 V battery (so I can connect it to the battery maintainer), then close the trailer. When I'm ready to go camping again I have to open my trailer again to put the battery in, then close the trailer for towing. Unsafe to stowe battery (12 V gel) in my SUV while towing. Can't connect battery maintainer while battery's in closed trailer, needs ventilation, etc. Any way around all this opening, closing, installing, uninstalling battery? Thanks, Juniper