Here is a few pics of my trailer hitch arrangement I made for my new trailer. It is very simple and cheap if you are looking for something in a seatpost attachment. The rubber fuel line acts a shock absorber sleeve, and it eliminates any slack or bumping when stopping and starting, slowing down or turning. The hitch pin (bolt) slides thru the fuel line, which is pushed into the eye-bolt and inserted into the bracket. It allows for full articulation and seems to work great so far. I used a 5/16 bolt with the threads ground off, then drilled a small 3/32 hole at the top for a keeper pin. The piece of fuel line I used had to be drilled through so the 5/16 bolt would easily slip through it.
As for the bracket, its an old driving light mount, pirated from my sons Dodge Powerwagon, clamped to the seatpost with a simple hose clamp. The white pvc pieces is from a pvc pipe cut in half, lengthwise, and serves as a sleeve to protect the seatpost. The inside diameter of the split pvc pipe is close to the 27.2 mm size of the seatpost. I opted for this arrangement because there is no way in hell I'm going to rig up a hitch post on my Columbus SL frame.
Cheap and very effective.
