I recommend something like the Stromberg Carlson Bike Bunk Trailer-Mounted Bike Rack Carrier for A-Frame Trailers # CC-275 which mounts to the tongue of your trailer and can support up to 100lbs.
This way this will avoid the spare tire on the rear of your trailer, and this rack will go over your propane tanks and attach to the frame of the trailer.
Alternatively, you can install a hitch to the rear of your trailer with # 13703 and a hitch extender like # BX88264 to push a bike rack out... view full answer...