you could pre drill holes for the foot rest in both locations and use the quick pins through the pipe instead if a set screw.
we did that on ours, it is solid and takes a second to move it.
our foot rest has quick pins to adjust the foot brace angle already, so we just pulled the set screws, drilled the holes and used the quick pins at the frame rail as well.
i would note, i did pull the fittings, pollished the shit out of the insides of the fittings and scrubbed a pencil inside the fitting all around.
graphite is a lubricant, helps the aluminum slide. easy peasy.
let me know if you want some help.
EDIT: seeing as your wife is the guide, if any of this baffles you, no pun intended, have her read it, it should make sense.