Popping in with an update. I've been doing lots of despooking with Tank and seeing some dramatic improvements in the majority of her life. She no longer shifts into her flight mode, where she just can't shift down for hours on end. Now, when something startles her she jumps and settles again. When there's something scary she may hesitate has even begun to investigate it.
She used to be a very "shoot first ask questions later" type of girl - but now she's really starting to ask questions and think about situations rather than just reacting.
I've started taking her for walks around my property every day (those of you who remember, Tank's biggest issue in life is leaving her stall/paddock - she'll freeze and refuse to move). I started the walks just by leading her with the target with the rope loose in my hand or over her neck. Her other issue involved with this is that when she feels pressure she feels trapped and panics - usually resulting in bolting back to her safe spot. So when I had her leading out confidently without any pressure, only following the target - if she spooked she could go away and come back. At first she would bolt all the way back to her paddock or where she last felt safe and I would have to lead her back out on target. Then gradually her spooks got less and less - each time staying closer and closer to the target when she spooks, now it's reached just a stationary jump/tense, then calm again. She stays with me 100% now, even when she's startled.
So now that she's good without pressure - I do hope to ride her out someday, in which case pressure will be used, at least for ridden cues. I can't have her feeling trapped and panicking just because I cued a left turn or asked her to stop if she's concerned about something. So I weaned her off the target and started using the lead rope, if she dragged behind or got ahead or stopped for grass I would apply pressure and bring up the target for her - C+T when she responded to the pressure, with less focus on reaching the target. Now the target is gone and we lead, when I need to apply pressure I C+T to proper responses, including stopping and standing when there's something concerning, backing up and yielding if she gets distracted. I always use non-escalating, light pressure with a C+T for the right response, so it's always her choice to respond correctly - the only response for the wrong choice is a lack of C+T.
We've progressed very well all around my property to the point she just doesn't care where we go on property any more.
So yesterday I had a friend with me, so we took Tank and my confident little pony out for a walk around the neighbor's farm and hay field (he mows paths for the horses). Tank was Wonderful! She would eat grass when I stopped, but as soon as I walked again she was back to following before contact was ever made. She was excited, but not afraid, and well behaved the entire walk. We saw the neighbors horses who she announced herself too, but carried on without an issue - she walked out well ahead of the pony who was having trouble getting out of the grass himself :P She was polite walking the way back too - without rushing. She was just perfect!