I ended up slapping together a ply wood box. Both batteries fit barely.
And the ply box I'd a wiggle and jiggle to get it into the frame.
Haft to put the batteries in after the box is in. Gotta tilt and slide them a bit. Not gonna be easy to steel. Our heads are just inches away at nite, and the dog hears and alerts real good.
It was just a slam it together box. We were leaving in a few days and the we're other task that had to be done also.
The lid would not fit so I cut the back of it off and put some roofing underlaying on it to carry any rain over the back and below the box proper.
Did not encounter more than a few drops do far.
Also have not really needed the batteries for more than a few minutes while setting up or rebooking to the truck. Had full hook ups so far. But plenty of battery juice makes wife feel better.
The box won't go in come out with wight distribution attachemens mounted. That is why the blue masking tape is on the trailer frame. I wanted to know exactly were to reattach them at.
I can and will do better latter.
Still need to install a power inverter and 4 dedecared sockits of it. 1 each side of the bed for our Cpap and bipap machines. On for mom's oxygen concentrator. And in the gally so we can power a crock pot sitting in the sink cooking our dinner while cruising down the highway.