I don't worry about a few scratches. They will buff out when Im ready to sell the bike.

Just ride.......

 

Never used anything for mine when I had throwovers, but here's a thought:

Go down to Walmart or whereever and pick up some of that plasticy/rubber anti-slip stuff and cut it to fit where your bag touches the fender.

Either that or maybe some felt velcro'd on the bottom of where the bag touches the fender.

 

When I bought my bike it came with a set of older saddle bags and there was a piece of felt that was cut to cover the rear fender where the bag sat. It actually worked so well that when I got new bags I kept the felt.

 

I don't use the throw-over straps anymore on mine (I solid mounted them now) but when I did, I used a piece of magnetic sign blank (used for door signs on vehicles) It sticks to the fender and won't let anything under it, like dust, or fine sand, that may scratch the paint. You can get it most sign supply stores. It's just a rubber magnetic sheet for lettering on. You can cut it with a sissors to any shape you need. PD

 

What if your fender is plastic (like the Aero 750)? Before I got my hardbags I used a piece of that non-skid stuff in black. It worked alright.