I think you can tow with a Sub. Just keep your pop-up box to 10' or less; say 1,700 pounds or less. Don't think you need any sway control. We have towed a pop-up from MN to the Rockies and back with a 4cyl Toyota. It works.
2012 F150 FX4 Ecoboost, 2016 Surveyor 274BHS
2003 Yamaha FJR1300, Demco Premiere Slider
1969 John Deere 1020, 1940 Ford 9N, 1948 Ford 8N
Jonsered 535, Can of WD-40, Duct Tape
Red Green coffee mugs