Your horse should be stopping at the back of the trailer and looking in or even stepping inside by now. I use an extra wide, extra tall two horse trailer. Once they become comfortable with a two horse, they can be loaded in the other types. I put a treat in the feed loft so when they do go all the way in it's a really nice surprise. If they are scared or uncertain it will take their mind off of the scary thing. In a slant load the extra space will allow them comfort.
Now you're at the back of the trailer asking him to move inside. Do this by asking him to walk past you into the trailer. Most of the time he will turn away or towards you. Stop this gently and ask him again. If he becomes really scared, move him around in a circle as in your lunging exercise, stopping him at the back. Yes, there can be a lot of repeating. You want him calm and repeating what you are asking him to do. Ask him to load up. Going half way in and backing out is fine, although you do not want him jumping out backwards. This is where a great whoa is important. He needs to be okay with his head inside the trailer before he will want to put the rest inside. It may take up to 45 minutes to get him all completely in the trailer, but taking the time now will get you a great loading horse every time. Shut the door and let him stand and get use to it.
When you are ready to unload, make sure he is standing still, not leaning on the door or rocking back and forth. Ask him to whoa; until his does this, do not unload him. If you start to open the door and he starts pushing, stop and have him stand and start again. When you do open the door touch his hip and ask him to back up. Give him time to do this. When he comes out, make it a bid deal, because it is. Let him stand and relax. Do some lunges around and then re-load. Keep everything relaxed and easy. Don't over do this.
The first thing you should have between you and your horse is Trust. If you've done the ground work, have your whoa, and have him moving off pressure, then bitting and saddling will be a lot smoother. You develop trust by teaching, not forcing, your lessons and by staying consistently correct. Make sure you have this between you and your horse before you begin.
Go back to the round pen and take a saddle blanket and saddle. Do your round pen warm up work. Always remember: Have a plan BEFORE you go out to work with your horse. Know what you're going to do and how to do it before you start. Don't just hope it happens.
If you have a bareback pad that will work best because it has a strap to hold it on. If not, open up a saddle pad so it's long enough to hang on each side and stay put. He should be fine with wearing this if you have sacked him out properly. Put the saddle pad on and do some of your round pen work. Then, add the saddle. If he is skiddish about the saddle go slowly and let him get comfortable with it. As I said, "if you did your sacking out he should be fine," so I'll proceed with the saddling. Put the saddle on your horse and cinch it up just tight enough to hold it on. Start moving him around slowly. You don't want him to fly around with the stirrups banging into the panels. Do your normal round pen work. Use the lead rope from the halter as a practice bridle. Make a loop that will fit from behind his ears to his mouth, hold the top of the lead rope over his head, and then slip the bottom end into his mouth as you would a bit. To have him open his mouth, hold the rope in the palm of your hand as you would the bit and place your thumb into the corner of his mouth. Then you can slide the rope in, pull it up in his mouth from the top as you would a bridle. Hold it in place for a few seconds then slide it out by slipping the top off first then let the rope drop out of his mouth. If he is receptive, repeat this a few more times. You may need to take some time with this and of course this is fine. You have plenty to work with till next time.
Take your time. Teach, don't force, the lessons and stay consistently correct. Have fun and happy training.
Tip: If you choose to bit him up with a snaffle, be careful not to hit his teeth with the bit.
