One "solo" dosen't make the trip. Have the new wanna be pilot demonstrate at least 3 seperate days of flying that he or she can do all the pilot stuff. That includes equipment checks, range checks, flight surface checks, start up and taxi work. Safety first always. I can relate to the taxi and ground handling issues. As a private pilot I had trouble learning to use the rudder (with the feet). I was instructed by my flight instructor to taxi "solo" onto the active runway and apply enough power to lift the nose wheel off the ground into just short of take off speed and travel the complete runway length on the mains. Full stop and turn around to do the same downwind. 1 hour of that cured the rudder work. Oh yeah I had to announce intentionson the radio as I did this.
Just don't turn 'em loose with 1 "solo". It ain't good!