The gasses that escape from the batteries could cause a problem with mounting close to the floor of the camper. Also, there could be a problem with road debris that would puncture the batteries, or the dreaded tire going flat throwing gators all over the place.
I wanted to go with a dual battery system when I 1st got my trailer, plus take some weight off of my tongue. I started this thread on RV.net: RV.Net Open Roads Forum: Travel Trailers: Dual Batteries on Bumper??
That was before I realized how weak camper bumpers were.
Chap , DW Joy, and Fur Baby Sango
2006 Ford F150 Super Cab 4x4
2008 Surveyor 263