I had to weld holders on to get 2 tanks. We leave one connected to the trailer and use the other on site with a propane tree to hold the latern and feed the stove or BBQ in the kitchen tent (First UP).
Pictures from both sides of the box installed, we had to extend the jack handle to clear the top of the battery box.
A "U" was made of angle iron and welded to the front of the propane shelf, and a flat piece of bar was welded across the front top of the A frame. Size and locations were determined by the battery box.
A notch was cut into the plastic just below the box handle at the front.
The rear handle was left intact.
The front handle rests on the bar at the front, the rear handle rests on the propane shelf at the back. Some of the weight
is carried by the "U" frame. Here is a shot of the battery box in place with the lid off.
You have to flex the box a bit to get it in by pulling the front rearwards to get over the plastic ridges so the front bar sits into the "notch". Once the battery is in, the box is difficult to flex and remove. We've been many miles over various terrain and never had a problem with the battery in or out.
The bottom of the box is about 10" above ground, my rear differential is about 7". I figure that is ample clearance. This is somebody elses work, not mine. I would have been a bit neater. But it does the job and you can't see the irregularities when the box is in.
Hope this helps. Let me know if you need to know anything else.