I'm in the process of removing my propane system (different story to be posted later once finished), and needed some way to replace the tongue weight from removing the propane tank. I have a Dutchmen Clamshell that only had a steel propane holder on the tongue. No room for the box.
Before:

After: I used a pressure treated 2x6, the original tire holder that was under the trailer, some angle iron, and appropriate bolts, fender washers, lock washers, lock nuts, and black spray paint.

