Agree with those who say it won't hold a charge more than a week or two without a disconnect. You can get a simple switch for $not$much$ or go high dollar with a latching solenoid type. For a trailer, I'd go Switch. Not just less expensive, there's no wiring to be done, and you aren't asking for a lot of amps as if starting a generator.
The good news is that with a disconnect, a good battery will stay "up" for months. I can leave ours off for 6-8 weeks and still crank the generator when I turn the battery back on.
