Have you tried to contact your RV's dealer? As far as I know, some of them - Jayco at least - offers the slide topper awning as an option. That will put it under their warranty if installed at factory.
I've been full timing for over four years in an Arctic Fox 27 – 5L fifth wheel that has a bedroom slide and a living room slide. I see a lot of folks that have slide awnings but I've never been convinced they would do enough for me to justify the cost, the NOISY flapping in the breeze, I was camped next to somebody once and their flapping slide awnings just about drove me crazy. The chance of a strong wind getting under them and tearing them up, in the winter I'm mostly in the desert areas and the winds can come up out of nowhere. And just another thing to break or complicate my life.
I'm sure they keep stuff off the top of your slide but I guess I've never been in a place where things get on my slide because it's never been a problem for me, maybe I'm just lucky