The closest thing we have to the dimensions you provided is the Adco SFS AquaShed RV Cover for Toy Hauler Travel Trailer item # 290-52277. This fits over the box portion of your travel trailer not the tongue or below the frame and is 40.5' long x 8.8' wide x 12' tall. view full answer...
For the Crossroads Hampton Destination travel trailer that is 38 feet in length we have the Adco AquaShed RV storage cover part # 290-52277 that is a confirmed fit and would work well. view full answer...