Although I am following this with great interest, I want to suggest to you that if you DO decide to pull off a raid or something like that, don't post about it here until it is DONE and the horse is safe in your hands. You did say that neither of these people has internet, but they could have friends who do and would tell them in a heartbeat. Just continue posting here about your difficulties getting help, who you are talking to, etc. Act like nothing is set up. Then BOOM! You've got him and they had no advance warning.
I am sending you every good vibe I can generate for the safe recovery of your horse!