If it were me, I'd drill out the old rivet and pop a new one in its place. I am not near my MH at the moment so I can't look at the step to confirm the layout, but I would suggest that would be about a 30 min job.
You can get a double step rivet repair kit. The problem with just drilling out and putting a bolt in is it usually the plastic spacer that has worn, the previous owner of our van just ignored the problem and the holes have worn oval so takes some sorting out now as the standard kit won't do it.
Rarely use our electric step!
Have a sturdy plastic one bought at a show for £18. Solid as ya like. Keep it in the garage. Never trusted the body mounted ones!!!
Ok in an emergency though and for 'occasional' use.