Originally Posted by Jordan S
Without draw reins I can get him on the bridle about 75% of the time(getting him on the bit during the posting trot is our biggest obstacle).
I think here that you might have a problem with relying on your hands for balance. Mind you it is only a thought (having not seen you ride) but it is normaly what I find the problem is when this sort of thing only manifests in rising (posting) trot.
As for getting him on the bridle, you should concentrate more on the back end rather then what the head is doing. It is a very rare horse that wont come into an outline when ridden from back to front, leg to hand. There are a few but they are few and far between.