AFTER LANDING ON A PAVED ROAD, THE PILOT SECURED THE AID OF A RANCHER TO ASSIST IN TAKEOFF. HIGH DENSITY ALTITUDE CONDITIONS EXISTED AT THE TIME WHICH REDUCED THE AIRCRAFT'S TAKEOFF PERFORMANCE. THE PILOT DID NOT ESTABLISH CLEAR PROCEDURES WITH THE RANCHER TO INSURE THAT THE ROADWAY WOULD BE CLEAR FOR A SUFFICIENT LENGTH FOR TAKEOFF. NOR DID HE ESTABLISH CLEAR COMMUNICATION PROCEDURES TO BE USED PRIOR TO THE TAKEOFF EVOLUTION. THE PILOT OBSERVED A HAND SIGNAL FROM THE RANCHER WHICH HE PERCEIVED TO BE A GO AHEAD FOR HIS DEPARTURE AND DURING THE TAKEOFF ROLL HE ENCOUNTERED A VEHICLE DRAWN TRAILER ON THE ROAD IN HIS GROUND PATH. HE ATTEMPTED TO CLIMB AND TURN AWAY FROM THE VEHICLE AND THEN MANEUVER AWAY FROM TERRAIN, HOWEVER, ADEQUATE CLEARANCE WAS NOT AVAILABLE TO INSURE THE AIRCRAFT WOULD CLEAR THE TRAILER. THE AIRCRAFT'S LEFT WINGTIP IMPACTED THE TRAILER AND A LOSS OF CONTROL AND GROUND COLLISION FOLLOWED.