Adult bikes can vary greatly in size and
weight. What do you have?
Bikes carried on the trailer cannot be taken to a ride point away from camp (unless you use a rack that can be transferred to the tow vehicle after you unhitch).
In my opinion a tongue mount is better for
weight distribution and less bouncy for the bikes, but it will increase your tongue
weight. Can your tow vehicle handle the extra weight? It can sometimes create clearance issues when backing.
A rear rack would be a last resort for me, and you have to make sure you maintain enough tongue weight to prevent dangerous sway. A rear rack should be mounted to the frame, which typically requires reinforcement (on my
Scamp it required welding in an extra cross member).
Not all bike racks are rated for use on a trailer. Check the fine print.
Inside the trailer can work, too, and a quick release fork mount makes them easy to get out of the way to use the trailer. After years of dealing with a troublesome rear rack, I moved ours inside our 13’
Scamp. Tows much better, and no worries about security, weather, or road rash.