According to TST, the repeater draws so little current that you can leave it connected to the battery. I didn't, I put a two prong
12v. plug on it and plug it into the Zamp connector on the side of the battery box. I mounted mine under the plastic cover for the propane tanks using industrial Velcro.
I called TST to inquire if there was an orientation for the antenna. They told me it doesn't matter, flat, vertical, or sideways.
BTW, If I didn't use the repeater the system still works just fine. I think it's more of a thing for fifth wheels and MH's.