I towed my Roo 19 (max GVWR about 4500lbs, although I was <4000lbs) with a 2011 3.6L Chevy Traverse for one season. Was not happy. Ran at 3000 rpm in 4th gear at 60 mph on flat and level. Some other Traverse owners (see Traverseforum.com), but not all, don't seem to mind running in 4th, but I was not. Went to the Silverado shown below (7500lb tow capacity).
I think the only other V6 you might find worthwhile would be the Ford F-150 Ecoboost.
1988 Coleman Sequoia - popup (1987-2007)
2012 Roo19 - hybid (2012-2015)
2016 Mini Lite 2503S - tt (2015 - ???)
2011 Traverse LT, 3.6L, FWD
2009 Silverado Ext Cab, 5.3L, 4x4, 3.73
2016 Silverado 2500HD Dbl Cab, 6.0L 4x4, 4.10