teaching a horse to drag logs/small trees to the barn

I was thinking of teaching Major to drag logs up to the barn. It's winter time and he's getting fat and lazy. Also, he seems more settled the more work he does and anything I can desensitize him to is beneficial. I don't want to do anything to mess him up or cause myself problems....so if you think this is a bad idea PLEASE SAY SO!!!! If it's ok to try it then here are my ideas:
I was thinking of saddling up as if I were going to ride and then walking him away from the barn and the leading him back with someone dragging a log behind us (not attached to him in any way) until he gets used to the sound of it. Then I thought I would tie a rope to the horn and attach a small log to the rope get him to pull that up. You think that would work? Or do you think I need some other kind of equipment? Or should I train him in a different way? Or should I not train him to do that at all (it's not a necessity}? I know it's kind of a strange question, but I'm seriously considering it, but I don't want to do anything that will mess up my horse or cause him to get hurt!!!!! That is the most important thing to me!!!