Hello Diver Dan,
Rest assured you are not the only one who
has considered such a modification.
The size and layout of your current Hi Lo
will determine what options you have.
For ideas you may have already looked
at the Trailmanor and the A-Liner approach.
www.Grainger.com might provide further
tub ideas, keeping weight a major consideration.
Truck campers often have clever solutions, too.
If considering an elaborate change, you may
want to construct a model first, to debug
potential problems.
Two sayings might guide your design,
"Keep it Simple, Sir" (KISS)
and
"Where there is a will there is a way".
Do please post pictures of your project.
GoCamp.
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