Its all about weight. Your bumper may or may not be able to support the additional weight - while traveling. You have to remember the bikes will bounce a bit (physics - things in motion!!). I tried this with a different trailer, after a 300 mile tow - when I got home the bumper assembly had all but broken away from the frame. Had a buddy weld two extra support bars (2" reese tubing) from the bumper back to the main frame - all was well......
Roselyn and Darrell
2007.5 Silverado LT/EFI Live Tuned Duramax/6Spd Allison/Banks Ram Air with Super Scoop/Edge CTS Gauges/Air Lift Load Lifter 5000 Ultimate Air Springs
2014 335ss Cruiser Provincial