There are several posts about the weight limit (150 pounds seems the most often quoted number) and what they all have in common is the "within 6 inches of the bumper).
Bumper weight rating
(Someone once posted a photo of a sticker on their camper's bumper with the weight limit, and I have been looking for it for a while now. If YOU have a sticker on your bumper I would like to see a picture of it.)
The bumper is designed for the spare tire carrier and that is it. Warranty void; if more than that is added. Some here will tell you that even THAT is too much.
As you go away from the bumper, due to leverage, the amount of weight that the bumper supports drops drastically.
To have the same amount of torque (and remember the torque in not constant due to bouncing - which makes it worse due to inertia) you would need to find out how much stress was on the welds and metal using the 150# within 6 inches number and then measure the distance to the last bike. Then solve for maximum weight the bikes and carrier can weigh.
Most likely only a carbon fiber bike rack will meet that requirement.
Obviously, it is your call what you do. Just don't expect much sympathy from the State Trooper as you explain the debris on the highway.
Rear Bumper Strength
From the Palamino Web site FAQ:
Q-Can I install a hitch to the rear bumper or frame of my Palomino RV product?
The bumpers/frames of Palomino RV products were not designed to accommodate this type of accessory installation.
The Sunline club web site bumper is rated at 100 pounds for a spare tire.
No accessories without frame modifications.