We have a 2011 284BHS with the battery tray right behind the propane tanks, less than a foot away, and I've seen them in similar locations on a variety of campers for years. There is also room for a second battery (on our to-do list), so I wouldn't be concerned with the proximity as much as keeping the wiring clean.
TT: 2011 Jayco Eagle 284BHS
TV1: 2010 F-250 6.4L Lariat 4X4 w/ Reece WD Hitch
TV2: 2006 Land Rover LR3 (not recommended for long trips)