I used "platform type" bike racks:

https://www.thule.com/en-us/us/bike-...on-9046-_-9046

Mounted one tray on each side of the trailer just ahead of the axle. I used two thin wall tubes to span the width of the trailer to act as receiver hitches on each side of the trailer. Then bolted two tubes to each rack tray, one forward and one aft on the tray so the rig is stable - I can sit on the bicycle while it's on the trailer - it's that solid.

The bikes hardly stick out to the side more than the trailer wheels, and are narrower than the tow vehicle. Due to being mounted aft on the trailer, added hitch weight is minimal.