Not knowing your truck or hitch capacity this idea may not be practical but have you considered using a hitch extension and having your bike hauler in between the trailer and truck. Take the weight off the back and add it to the front. I had a trailer with a factory installed cargo carrier on the rear bumper and anything besides a few lawn chairs on it would make the trailer unstable. I don't know the math but rear fulcrum weight seems to overcome tongue weight weight very easily. Too much tongue weight can be compensated with a WDH but too little has few options that don't include un-necessary weight.
