8 years ago or so I shipped a DG-303 in trailer from Flordia to CA. Used Peterson Transport from Kansas, not sure they are still around. You need to look for trucking companies that handle transporting mixed loads/equipment on a low-loader. Not the folks who focus on carring cars on car transporters.. And some of this requires you to just get lucky to find a carrier willing or already planning to go your route and able to double up load etc. to avoid it being too many $k. I got lucky and just saw this company mentioned on a glider forum. I think he had an antique car (well covered) and parts/assembly for earthmoving equipment on his trailer on this trip. Either way look for carriers with major business near either/both ends of your route.

Finding a glider pilot/crew member who is experienced towing gliders and paying them may be easier--but your trailer better be perfectly road worth. And double check insurance etc.

Darryl