Thanks everyone for the advice. I like the lunging idea, so I will probably try that.
We do have pastures that are separated from the main one, but our property is all on a hill, so it would be very difficult to get the trailer up and down, and once its down the hill, there is no where flat except for the small paddock itself. My dad has been filling in a dip in our other field so he can bring the trailer up there though. However, he originally thought she was going to give us a big problem and wanted to train her in an enclosed area. Turns out, she is very calm about the whole thing, so we've been able to work with her out in the open.
I've already tried just walking her up into the trailer and she follows me only so far. She'll put her whole head in the trailer and maybe a foot or two and then just stops. I praise her for every step she takes and she loves it. She's never flipped out, even with strange squeaks and noises from the trailer. That's not to say she couldn't kill me in an instant, but this horse is much less likely to compared to our Stetson!
I haven't really worked with her and the trailer all that much yet, so its not that I've run into a blockade. Its just that I am looking for some good ideas before I start getting real serious. I am actually not nervous at all with this horse. She responds well to pressure and release, so we've been putting pressure on the halter for her to move forward (with clicks) and when she does so, or steps into the trailer, we praise her like crazy. That works for the most part, but I wanted to see what other methods people use. The last thing I want to deal with is a horse that has trailering issues! (As it seems so many people out there have!)
Thanks all. Once this rain clears up, I'm hoping to get out there. I was supposed to go trail riding today with our other horses and of course it rains!