....or pull the fuse in the red connector ( has a cap on it) on the frame rail just above the breakaway switch.
this fuse ( 20amp) allows the CO/LP detector to work as well, and thats the 'other' draw you are having on the battery.
FYI, there is a frame across the tongue between the box and the LP tank, you can set 2 batteries in boxes in this frame ( straddling the lift cable from the winch ) and then have added room for a second LP tank on the plate, or a mounting place for some other gadget on the plate. My dealer tech didn't know that batteries would fit there when asked (maybe I was expecting too much?).
I have added a second battery to ours and mounted them on the frame mentioned above, roof winch performance was greatly improved, lights don't dim as much when operating strictly from 12v.
have been using camper in driveway the last 2 weeks, battery voltage was down to 12.3v, about 70%, not too bad.
at some point I will replace the wiring from the batteries to the converter and inside power box with heavier gauge, should reduce voltage drop further ( less dimming of lights when other 12v appliances are operated). as $$ allows, will also convert all lighting to LED.
get the15amp/30amp adapter, it's cheap and worth it, and get a GOOD extension cord, 12ga wire minimum, 50 ft. don't let your battery get too low, the converter/charger doesn't like charging dead batteries.
'12 Flagstaff Classic 625D
'97 Toyota 4Runner