Kevin-
I thought it odd I've not noticed that rubber bumper on my 2001 as I believe we both have the Philips doors of that era. I took a look this morning and see I don't have a bumper. A previous owner must have removed it. I see the screw-hole for mounting it, the outline of the bumper, and a mark on the door frame where it used to sit. But no bumper.
My door works fine without it but of course we wonder if that could lead to a problem later on.
Replacing the washers doesn't look easy. It looks like it would require removing at least part of the door frame from the camper. And a simple swapout may not be a good answer anyway as it may not be the washers that are wearing.
I was also thinking it may be possible to use a dremel to notch two very thin washers (the horseshoe-washers idea) to shim the door up a teeny bit. I'd probably try to make them an interference fit with the center rod but perhaps glue or epoxy the new washer edge to the old. Come to think of it, I'd probably just try to hot-glue the edges. ( I do see, however, that the spacing is different on my two hinges. One is .020 and the other .035 inches so washer selection could be an issue)
Also- I've adjusted household doors with a bit of shim material under a hinge. I'd consider trying a piece of aluminum flashing or soda-can aluminum under the bottom hinge (if I had a problem).
Realistically, though, if I didn't get a better answer from FWC/ ATC, I'd just go ahead and shave the flat side of the bumper and see how it goes. I don't plan to do anything about my missing bumper but will be checking the door occasionally for hints of a developing problem.