I backed my two horse up against a roundpen that was open on the other end to the pasture. I secured it with jacks outside the roundpen and tied the doors back and tied the panels. I put the recalcitrant loader in the pasture with a fearless go anywhere gelding. I then put grain in the mangers twice a day. Of course he went in and started eating immediately. Within one day she was in there also. After a couple of days I started closing the doors on them while they ate and opening them in about 20 minutes. On the day we needed to leave I just hooked the trailer up to the trailer, fed, they loaded, I closed the doors and off we went.

My only warning - if your trailer has foam padding as mine did you might want to remove it before you do this. The gelding had a great time removing some of the foam and playing with it.

So you'll have to borrow or rent a trailer for at least three days to do this but it works really well.