I put the sandpaper like stair tread tape on my slides to flip the seal. I mounted it about midway on the slide so it flips the seal each way as the slide is extending or retracting. I am now approaching 90,000 miles with this coach and if the tape is causing any wear on the rubber seal, you can't tell it.
I should add that this flip seal is not the main seal for my slide. When retraced there is a bubble type seal that prevents moisture from getting in to the coach. When extended, a similar bubble type seal is used to keep out moisture. The flip type seal is sort of the first line of defense.