I was going to use a rivnut tool on the inside of my van for other things, but I don't know if it will work here because of where the holes are. Though, I've never used one.
The hole is only just barely too big for the included screws, so the suggestion of a larger fastener may be the solution for me. It's just one hole.
The only thing that came with my ladder was a bag full of screws. https://www.carid.com/2006-ford-e-se...ification_mail
Thanks everyone for your suggestions, I'll see if I can use a larger fastener first.