The exact answer will depend on your wheelbase and the distance from your rear axle to the center of the bike carrier. However, given those weights, I'd estimate that you'll need at least 1200lb capacity on your rear axle, maybe 1400lb. What's your current rear axle weight and what's the GAWR for the rear axle?
2008 King Aire 4562, Spartan K3(GT) w/ Cummins ISX, Motosat HD-SL5 w/ SWM-8, Multiswitch, HR34 Genie
2014 Jeep Grand Cherokee Overland 5.7L V8 Hemi w/ Blue Ox Aventa LX Tow Bar and baseplate, SMI Air Force One brake