I know I'm not addressing your question here, but I wanted to suggest something from the fiberglass boatbuilding world. If you really have the trailer gutted, and the rivet holes filled, you might consider re-attaching your cabinets, etc. with fiberglass tabbing. Not only would the tabbing create a much stronger structure, but you would have no holes.
You could either fillet and tab directly, or you could 'glass a cleat to the shell and then fasten sideways into that.
For things like large structural bulkheads, it's advisable to create a gap (with foam or the like) between the item and the "hull," but that's not usually necessary on smaller items.
So likely not on the kitchen cabinets.... maybe on the closet.
If you don't have the Ensolite down, then you probably don't want to consider this. And it's certainly not necessary; just an option.
Of course I must beg for photos