The wind resistance will be much lower. Therefore, the penalty should be less. We pulled a large popup, with slide out, A/C, and plenty of stuff (4000#). We bought a TT, which was only 1200# heavier (loaded), but had the big sail on the front. The mpg went from 11-12 mpg to 5-6 mpg. We quickly decided to move to a diesel f250.
Ben and Doreen
Home Away From Home - 2017 PT Crusader 315RST
TV - 2008 F250 Lariat 4X4 6.4 Diesel
42 nights camping in 2015
49 nights so far in 2016 (Still Not Enough!)