Nope, the Sunspot isn't the 13.5'. It's 10.5', and as far as I know that's from tongue to bumper. After that, there was the 12.5 MC, which was the shortest coach that you could walk in. It also had a rear dinette and front kitchen. The 13.5 RD was basically a mirror image of the 12.5 MC, but they added a foot. The brochures should give you specs for all these coaches.
The Sunspots are very hard to come by. If you find one, make sure to pass the word. The early 12.5 MC's are extremely hard to come by, but the newer ones ('78-'82 or so) are found more often, and the same goes for the 13's.
2007 T-286SR Cherry/Granola, #6236, original owner, current mileage: 9467.8 (as of 5/26/19)
1997 T-2653 Blue Denim, #5471
1979 12 1/2' MC, Beige & Avocado, #4639
Past Sunlines: '97 T-2653 #5089, '94 T-2251, '86 T-1550, '94 T-2363, '98 T-270SR