I much prefer the batteries on the back of my 17. It leaves space for lawn chairs and other long, light items for the storage box. With dual propane & an electric tongue jack I have no problem getting enough weight on the hitch - in fact I have to be careful what I load in the front storage box to keep it under the limit of my RAV4 (350 lbs).
In addition to the electric cord & hoses, I keep my grill, a small folding table, 2 lawn chairs, and a couple of small plastic bins I use to keep cleaning supplies & ant spray, WD 40, etc in the front box. By the way, an interesting thing happens to a bottle of liquid wax stored in its side when you go from sea level to 8000'. Don't ask how I know or how long it took to clean up the bin!
I have had a small leak, for some strange reason, only on the passenger side, when towing in driving rain. I drilled an 1/8" hole in the outside bottom of each side of the box to drain what little accumulates.