I've taken care of the problem and the solution works very well with minimal effort.
The problem with any protection on the fender was visibility since the rub is in a visible location without a passenger, thus protecting that portion would have made the protection visible.
This solution is invisible with pillion pad on.
I went to the hardware store and picked up two #7 rubber stoppers. Cut off the lower 5/8" (approx.) and is what is used under the seat.
I grabbed my trusty industrial strength velcro and cut it to size for the top of the stoppers. This is quality Velcro that I have used for similar things. The adhesive is extremely good stuff but can be removed. Great where constant pressure is being applied like under the seat.
For fender protection from the bumper, I just cut out some small rectangles of window cling or (vinyl static stickers would work) and put them on the "CLEAN" fender, add the pillion and it’s done.
Here are some images.
Bumper Placement under PadUsed industrial velcro for bumper to covering. The good stuff.
(Ignore the velcro you see on the pan - that was my first test and in those positions, they don't help at all.)
Static Adhesive / Vinyl Static Cling / etc. on fender This stuff goes on and comes off clean. Even kids vinyl static cling stickers would work well here as they don't move and don't gum up the paint.
Low tack vinyl tape might work, but the adhesive will probably heat up in the sun and make a mess.
I just have to make sure the fender is clean as I don't want any debrit under that stuff where the bumper makes contact.
View up under the seat.The bumpers are in constant contact to a relative flat part of the fender so there is no tipping, rubbing, bumping, sliding or shifting.
Invisible to all The coolest part, it's invisible externally and only adds about 3 seconds to going solo because I have to pick up the static cling. Of course, I could just leave it and it would probably blow off.

I had my wife butt-test the mod and squirm around to try and get it touch, shift, etc... Nothing. This thing doesn't budge, tip, rub, or move at all.
There is still a little tweaking to do, but for now - no more rub marks.
Best $3.27 mod I can think of for this bike.