I decided to take a crack at it from another angle. Though I don't think I'll use clicker training as religiously with Snickers as I do Flash simply because he's already had 30 days on him, I do want him to understand the concept in order to solve issues such as these. Unfortunately, Snickers hasn't been quite as eager of a learner as Flash, but that probably has something to do with the fact that he's been given treats and grain regularly just for looking cute and has never had to work for them, while Flash has had to earn his from day one. Plus, Snickers has other trainers and people working with him and is quite a bit older. However, after some work on Friday and this morning, he's finally got the concept! He's deliberately and repeatedly touching my target :) Again, he's not nearly as eager as Flash, but he gets what's going on. (I think he was also full and wasn't as excited about the treats I was using, since he eventually stopped eating them even when he did earn them).
When we reached that point with targeting my water bottle wrapped in lime green duct tape, we moved out of the stall and took a short brushing break before taking a crack at the bridle issue. I changed treats and took it slow - he got it pretty quickly too! First I got him to lower his head when I presented the bridle, then to allow me to put the headstall around his head (not on him though) and then lower his head, and finally to let me put the bit in. He's not keeping his head nice and low and relaxed, especially when I'm putting the bit in, but he's not throwing it in the air, either. Improvement and baby steps :) The final time, I even got the headstall around his ear, though he was pulling away a bit. That's a good point to stop, I decided.
Tomorrow afternoon we'll pick up with the bridle, stepping back to simply lowering his head when I'm holding it around and on his head, and hopefully get that bit into his mouth and bridle completely on a couple of times with lots of rewards :) It'll be tempting to ride him if we get it on in time, but we'll see if I actually do. I wouldn't want to ruin it for him by working him in a bridle when he's still not sure about how he wants to react to it being put on! My main focus right now is going to be on Snickers and I getting used to each other and the more urgent issue of getting him to take a bridle nicely. Like the board says, No Snarl Mr. Snickers!