During my LE career, afterwards, and go to this day, I have used a 2" receiver and a receiver hitch made by Hollywood Bike racks. I ordered a rear trailer hitch with our trailer. Two things that you need to be aware of. NEVER trust the devices that the bike rack manufacturer puts the rack to hold the bicycle. Always us a rope or other tie down to help hold the bicycle. Always put a lock on the pin that holds the rack to the trailer or purchase one of the pins that had a lock built into it.
I second the motion on having a hitch on both the trailer and the truck. Makes it easy to transfer the bicycle from the campsite to where you are going to ride. At night I throw a cover over the bicycles (or if it looks like rain) to keep the moisture off the bicycles. I have used Hollywood bicycle racks for years and in fact I have one for the trailer and one for the non-towing truck at home.