The Classic Accessories Deluxe PolyPro III Heavy-Duty Cover for Class B RVs # CA80103 that you referenced will fit your 2017 Roadtrek SS Agile and will also be able to fit around the spare tire as well. This cover is designed for Class B RV's like yours that are up to 60 feet in length and I looked up the length of your RV and it's 19-1/2 feet long. view full answer...