Great job - I am planning something the same here for my OFF-ROAD POPUP trailer new batteries sitting on top of the trailer frame between the PROPANE TANKS and the trailer front deck.
About the only thing different I will do here is use round head STOVE TYPE BOLTS to go through the trailer frame from the bottom and have the bolts and washers inside the the bottom of the metal box. The round heads would be more difficult from cutting off and losing the whole battery box with the batteries and things inside the metal box
I will have wood strips on the inside floor of the box for the batteries to sit on anyway allowing for draining of battery fluids if they ever boil out on me.
I too am planning on storing some outside items along with just two 150AH Trojan T1275s batteries. The charging fumes will eat up almost anything metal left inside the box. The compartment wall is a great idea.
I was never happy with the torklift method of locking the sliding top. A hole for a PAD LOCK could very easily be cut for gaining entrance. Maybe one of the solid key type locks. I really prefer the side mounted twist level locking latch but you sure can't go wrong with the TORKLIFT price. I'm sure I will mod it like I want when I get one...
I have made it safe all these years with the batteries sitting in their plastic holders with lids and probably when I really make one safer against from thief they will steal my whole off-road POPUP trailer hehe...
Again nice job...
Roy Ken
My Posts are IMHO based on my experiences - Words in CAPS does not mean I am shouting
Roy - Carolyn
RETIRED DOAF/DON/DOD/CONTR RADIO TECH (42yrs)
K9PHT (Since 1957) 146.52M
2010 F150, 5.4,3:73 Gears,SCab
2008 Starcraft 14RT EU2000i GEN
2005 Flagstaff 8528RESS