The Solera 8 Foot Slider (Slide-Topper) # LCV000168106 referenced in your question is designed for a box width range of 86 inches to 91-3/4 inches. When measuring your box width, you will want to measure from the outside front of the box, including flange. Since your box size with the flange is 94-1/2 inches, this will not be the correct fit.
I instead recommend the 8.5 Foot Solera Slide-Topper # LCV000168107. This will work with a box width range of 92 inches to 97-3/4 inches so it will... view full answer...