Done the rope thing too, extensively, while I was prepping her for breaking. I ride English but it's pretty much one of the default methods in my toolkit so they don't fight being girthed up for the first few times. My horses ["mine" meaning those I have had any part in training... not many, I'm only young and don't have a ton of money so can't take projects constantly but still] are all absolutely fine with ropes looped and tied and flicked around all parts of their bodies. Getting in near the udders is a bit hard though!
This one is a paradox. She's quiet, but she's crazy. She's the easiest horse to train I've ever had the pleasure of working with, but the hardest as well. She has huge issues, but she's largely unspoiled and incredibly trusting. She hates men, but she will choose to demand cuddles from men over women if there are any men around. She's a nightmare about her feet, but she's a dream about her feet. She's consistent, but she's unpredictable. She's reliable, but she's dangerous for the wrong handler. She's a good doer, but she's a hard keeper [that one I can explain - she keeps weight on easily enough but HOLY HIGH MAINTENANCE o.o there are SO many feeds that she can't have because they send her lame, the one thing I've found that's really working so far is beet pulp]. She's not a kicker, but she's lethal with those hind legs. She's sweet as pie, but if looks could kill...
...her neighbour would be a dead horse. [edit; I do NOT tolerate these faces being made at me, or while I'm between them or in the box with her, and she doesn't follow through with the looks or I would do something about making sure she can't/won't kick out in his direction]
EVERYTHING about her is a paradox. The level of fear she used to have had to have been man-made, but this reactiveness and sensitivity is just... who she is. A less sensitive, less reactive horse would never have turned dangerous or been that scared... the guy wasn't THAT bad, not abusive, just... "forceful" I guess is the word. The thing is, she can't BE forced, she is The Great Almighty Queen of Her Royal Domain and everything has to be a 'discussion'. You know what they say. You tell a gelding, ask a stallion, but you must discuss it
with a mare. She needs to think it's her idea.
Thankfully she is by nature a horse that is incredibly willing to please, or she would be an absolute nightmare. So mostly, if I ask her to do something, it's "her" idea, because she wants the approval. She thrives on it.
I didn't actually ask for advice, by the way :) I was just sharing my thoughts for the benefit of the OP, because I have a filly who is utterly impossible about cleaning "under there". Back end is so easy it's not even worth talking about, but underneath is just... ugh.