I too am interested in adding a topper to the slide out under the awning.
The topper and the awning each serve a different function. Awnings are for when it is nice and you want shade. They are to be retracted for wind and storms. That is why most of the new awnings have wind and rain sensors that auto retract them. The topper is to provide the protection to the top of the slide during rain and snow events and will shed all of the debris that piles up on top, be it leaves, snow, or pooled rain water all while protecting the upper slide seal and from bringing unwanted stuff back into the RV when pulling in the slide.
If you don't retract your awning during a storm, you are just asking for the wind to rip it off the side of your coach. At least that is what I have observed happening to others on several occasions here in Kansas. We just don't get gentle storms here on the plains.
We have four slides on our new Newmar and three of them came with toppers and the awning is intended to cover the fourth. I tested it during a light gentle shower by extending it the 2 feet to just cover the slide and sure enough just as soon as it started to sprinkle the awning auto retracted. I called Newmar to ask if a topper could be added to this slide out and they said that it could not for two reasons. First they said they intentionally left this topper off because in the past they have had numerous complaints of the awning snagging it during operation and causing damage. Second they said because of this they no longer put appropriate structural blocking in the slide out structure to accommodate mounting a topper.
I took them at their word, but I am dissappointed. I have always had slide toppers and they work great in all four seasons and inclement weather. I may find someone with a density scanner to see if the structure is present on my slide just to see if I could add one, but for now I will just take my battery operated leaf blower with me to blow off the top of the slide before I retract.
[purple]WILLIEBAGO[/purple]
2019 Newmar Baystar 3626, F53, 252"WB with 6.8L gas engine
2003 Jeep Liberty Limited Toad
2 cockapoos, Jordy and Nelson, who love RVing
[purple]Go K-State Wildcats[/purple]