Brian,
I believe your situation is different than the OP's trailer. Yours has a "main awning" mounted on the trailer sidewall, a "secondary awning" mounted on the curbside slide. Installing a slide cover on top of that awning and adjacent to the main awning arm would/could cause a clearance issue and might require a "short installation" or "shifted installation" to gain the needed clearance.
The OP's 260MLE has two slides, both on the roadside of the trailer and each is at opposite ends of the trailer. There's nothing to cause a clearance issue on that side of the trailer that would create a need to install shorter slide covers.
Here's the floorplan and a photo of the two roadside slides.