Hi There,
I hate to be the one to say this, but your stress will immediately be reflected by your equines (at least, if donkeys are anything like horses)! So, avoid training while you're feeling stressed. (I know, easier said than done.)
Now for the good news... Take a deep breath, and ask yourself, what's the worst that can happen? I've been embarrassed many, many (many, many, many) times by my minis, and - it's not so bad. It's survivable, especially if you can laugh at yourself (or them). And the fun of the show is way worth it.
You're going to a show! That should be a blast! People and beasties to watch and chat with, and you can show yours off to everyone and get lots of compliments. Think about the fun, and forget about the showing stuff. Drink some hot chocolate (or your beverage of choice) and envision yourself and your donkeys graciously thanking the judge for that blue ribbon...
Okay, so now recruit a friend to help with the Coggins and do some practice loading sessions. Got treats? Act like you've got all the time in the world, and this loading thing is soooo much fun, you know they're going to love it! (Because, if they don't load, they don't get to go to the show and see their buddies, right?) And, if one's not behaving, ignore her and work with your perfect equine (jealousy is a great motivator) and your naughty girl will come around. (It worked for my 20-year-old soooo stubborn mare!)
I know I'm being a little silly here, but I have done the stressed-out thing and it really takes the fun out of training and showing - so if you can laugh at me and my advice, and relax a little, and think about the fun, I bet things will go better. (And if that doesn't work, picture me and my mini driving out of the show ring BACKWARDS - from the middle! - because my she decided halfway around that she was Not Going To Do It. My face was beet red, everybody was laughing, and I felt like digging a hole and falling into it. But, like I said, I survived, put her back in her stall and went to get some fried dough and Did Not Share.)
I do hope you have a great time at the show, and best of luck.
Lori