I use to haul mine on a truck rack and over the cab. I've seen some that used a 55 gallon drum in the very front of the trailer to put the big end of the tipi poles into and then support the back much higher like ksnow has mentioned.
Growing up near the tee pee capital of the world the majority of people used a frame built from poles in the pickup box year's ago , any more most use a pipe or ladder rack mounted on their pickups and ratchet straps to hold them down .
You could take a look at photos on this website Marty. I also used duckduckgo and found several photos of tee pee pole trailers. http://www.polespecialties.com/index.html