Please please PLEASE don't sedate the horse! The worst thing you can do is sedate the horse to load it. Horses can react funny to sedation and you do NOT want her exploding in the trailer halfway home.
I have to load and unload unbroke horses quite often. The easiest way to do it is to use a 4 horse stock trailer. I pull it alongside a barn etc so that the barn wall forms one side of a chute. Using some pipe panels you can use the open door and the panels to form the other side of the chute. Have the horse herded into a small pen attached to the chute, then once she is in the chute close the pen. Slowly use the panels to crowd the horse into the trailer. She WILL go in. Once she is in shut the back door. If you want to get her into the front compartment let her settle down, then creep into the trailer and SLOWLY shut the gate.
I don't tie my horses when I trailer them. I believe they need to have their head free so that they can balance themselves. I would NOT use this opportunity to teach horse to tie.
When you get her home BEFORE she is unloaded, snap a 20 foot or so line of thick rope onto her halter and turn her out. She will step on the rope constantly and stop herself. She can't run with her feet on the rope! You can slowly start handling her safely this way.
Spent a whole hour today laying in a pasture, waiting for a sparkling vampire to show up. Alas, I woke up and looked over, only to find a mound of horse crap. Sigh.