Frighteningly poor ground manners
I'm currently pony-sitting my neighbor's little herd, and she has a bit of a problem gelding. In the decade since she got him as a colt, life apparently came up so he's still incredibly green. Additionally, he's a very anxious boy with many tics and dislikes.
He's very mouthy (especially when he's nervous)- biting anything in mouth range, being it the dog, my arms, or the other horses. He paces and paws both in the barn and in the field, and typically encroaches on my/other horses space. In the past year since I last watched him, he's also become more prone to striking out with his front hooves (most especially at the dog, but surprisingly also at me) as well as bucking, kicking, charging, and crow hopping at anything remotely threatening- which can include being near the dog, being near another horse, being in proximity to the barn door or paddock fence.
So being that his owner accepts his erratic behavior, I don't intend to do much in way of re-socializing or training him, but for my own safety, I'd love any suggestions about working with him for the next week. I've started leaving the dog in (so she doesn't antagonize him, or the situation doesn't threaten him) and I've found that grooming helps his anxiety (but conversely lends to being more pushy). I'm also trying to make his routine more structured, so he both feels secure and starts to recognize boundaries.
Any other ideas on how to clean up his act?