Or if you so choose, just put in one of these...(SIMPLE install)
http://www.lslproducts.com/ToadChargePage.html
It will keep your battery charged from the coach alternator. (Only when the coach is running and thus a + charge current is present.)
For me, I have one of these, I in the Saturn I need to pull a fuse or mileage get added even if the Outlook is not running. I mention this for you may care to look at your mileage when you head out and then check it to see if it going up. If it is, then I guess you would need to disconnect that battery anyway.
I did not use the tow bar connector, I wired right into the main cable that I run from my coach for the lights on the tow. One of those, I forget which, has the live 12V that comes from the coach. So when ever I have the electrical cable hooked to the Outlook, it maintains the battery with this unit.
Side note...They also have this to keep your coach starting batteries charged up when you are on shore power...
http://www.lslproducts.com/TLSPage.html
Again, simple install.