Rumer in harness

Rumer has changed a lot since moving into the paddock with Percy and coming in each night. The paddock they are in has direct access to the barn aisle for their run-in so I need to go through several times a day and squeeze past them to get in and out. This has resulted in a lot of casual contact for her and she has become much more relaxed and like a pet pony!
I have put her on the cross-ties as least once a week for grooming sessions while trying to shed out her wooly mammoth pony coat! I have been able to progress to "clicker free" grooming sessions. She no longer needs the reinforcement of regular clicking to be comfortable with having body parts handled. I proceeded from clicking every 10 curries or brushes, to every 15, to just once per body section (neck, barrel, rump) to not clicking at all for her body but yes for her legs. The last time I groomed her I was able to groom every inch of her without seeing any expression of concern.
One day I decided to try putting the surcingle and breeching of the harness on her. I had clicked her to comfort levels with the surcingle last year and had done the same with just the breeching earlier this year. After grooming her, I took her to the round pen, thinking that if she did explode, she'd have a safe confined space to do it in. But it was a windy day and she was feeling spring sillies so I stopped at the surcingle and just had her wear that around the round pen while we worked on head down and stand on a mat. Even this was a little too much for the day- her head cocked to the side the way it does when she is worried about something. I felt lucky to be able to do what little I had and called it quits without any blowups.
Several days later, I tried again, and this time she was so relaxed that I decided to go ahead and try putting the harness on her while she was cross-tied. You can see from the photo that it was a different day, different story. She was very relaxed with the surcingle and so I added the breeching as well, little by little. First I just laid it on top of her rump and C/T'd for legs not moving, then removed it. Then I did the same but slid it partway back to her tail- C/T. I continued this process until it was sitting in the proper position, then I left it and just C/T'd for duration while she stood quietly. Reading her mood, I thought we could do more and so I began lifting her tail and C/Ting for that. As a little filly who kicked like a mule as an hours old foal, I knew to take this piece very cautiously. I started by just touching her tail- C/T, then wagging it slightly- C/T, then moving it around more and C/T. The big difference I saw in this work is that she now understands the game well enough that as soon as she got clicked for my touching her tail, she knew to keep her feet still and that I would respect her concerns so she could trust me. As a yearling, she was a lot more hesitant to trust me when I showed up with new ideas or objects. Now her attitude is more of a "oh, what are we going to play today?".
After manipulating her tail a fair bit, I held it up just a little and wrapped my finger under it at the top the way a crupper would- C/T. Her ears told me she thought this was a bit weird, but if that was the game I wanted to play, she would play too. I progressed to the point where I put the crupper under her tail but I did not try to buckle it. Then I stepped away and began taking pictures. This was an opportunity for her to stand while I moved away and returned and walked all around her. After a bit she got impatient and started pawing so I waited until she stood still- C/T and then began removing the harness.