jumpit89 wrote:
Do I need to be working on the trailer while I'm working on "forward"? Or do I need to wait until we have forward firmly established?
Again, I'm just speculating since I can't see you and your horse's interactions, but I would work forward around the trailer...just not necessarily IN the trailer. 

Here's another example.  My hubby has been doing a lot of work this past year with his horse, too.  She's way more mellow and laid back than Holly, and most of the time, will "go along" with whatever he asks her to do.  So in his mind, she's better trained.  But he found out that she's terrified of fireworks...and when she gets scared, he has no way of "bringing her back" to him because he rarely ever has to do that.  The fireworks have shown him that there's a big hole in his relationship with his horse...it's always been there, it's just not obvious until something "bigger" occurs.

So you could work your mare in the same manner you've been doing and she's going to be fine.  You need to go beyond that and work her in situations that challenge you both...and if having the trailer near by does that, then great.  Let the trailer be the distractor, but still, don't make it about the trailer...make it about her listening to you.