Wondered what you were doing with horses on planes, xquestrian!
What tricks? Look up ImagineAHorse, Nevzorov's Haute Ecole & other trick training sites for inspirational ideas. I find that 'fetch' & soccer(with a giant ball) are 2 games that horses tend to really enjoy.(look up friesians playing soccer on youtube too!)
Of course your donk is going to try to get the reward as easily as possible. If you're only starting out with treat training, I would suggest you first study the principles of training, and teach your donkey some basic rules & 'manners' to begin with.
I'm gathering you're starting out by 'luring' the behaviour - showing her the carrot & moving it away to get her to follow it & bow? I don't think there's a problem with doing that initially, but I wouldn't keep doing this for long, or you get 'side effects' such as them doing as little as they can possibly get away with to get the reward, snatch & run type behaviour, etc. After a few repetitions of her following your hand with the carrot, then start doing it without the carrot & as soon as she 'targets' your hand or otherwise begins following the cue, then you say 'good' & give her the treat.
You need to make every step of the exercise pretty easy for her to get right and increase difficultly only gradually, so she still succeeds most of the time. If she fails too often, especially in the beginning, she may give up & quit trying. Eg. You might start out reinforcing her for just putting her nose between her knees. Then you might ask her to put her whole head between her knees, or hold it in that position for a short time. If you try something that she obviously doesn't get, then there's also not far to back up to get back to success & then just work towards your goal a little more gradually.