Gilly and the Trailer

My neighbor and riding buddy, Kim, got a trailer so now we have wheels!!! Yippee!!! We can haul the horses to trail rides and anywhere we want to go. How fun. Gilly is not so sure about it though. Here he is at the beginning of his lessons.
Good boy, going into the trailer that far. See Gilly will get on a trailer but doesn't like to back off. We what we are doing it just going in with the front feet, leave the hind ones on the ground for now.
He is smelling the inside of the trailer and chewing on everything in sight; checking it out. He likes looking out the big windows in this one. I let him stay on as long as he wants to, then he will back off by himself. Then again, back on with the front feet. I don't want to make him get on, forcing him to get on will only make things worse. Each time he gets on by himself he builds confidence and it will be easier then next time.
He did great and this was about the end of the lesson yesterday. I am reaching out with the stick and string only to lightly tap him on the rump to encourage him to move up a bit more. When we are finished with his lessons on this I will have him going into the trailer with me standing beside it. I want him to load and unload just by my wiggling the lead rope.
Pokey will have to learn this also. But for now he is saying, "Nah, I don't think so". Pokey of course will not be going with us in the trailer but if he should ever need to make a trip to the vets office I want him to be able to get on the trailer too. He will be a tough nut to crack though, donkeys thinking pattern is much different than a horse's.
Maybe we can just roll him in, think????