Located to the left of the sink, two aluminum braces fastened
to the side of the cabinet, one over the other, the upper one
with a round handle made to fasten something in place.

The folding
bench seat does not make use of this as a support (an initial guess)

It appears to be original equipment, or at least is as old as
the Campmobile. Was it made to hold a fire extinguisher?

Feel free to reply with guesses, answers and late flames.