It looks like you've got advice on getting it out of the shop and onto the trailer. The big threat is transporting it on a trailer and not having a major issue. While a mill isn't extremely top heavy like a lathe or other machines you absolutely, positively, can not let it move at ALL during transport or it can topple when you hit a bump or have to swerve/brake hard because of some idiot on the road. Not pointing fingers, but 9 times out of 10 when we see pictures of people with machinery on trailers they aren't secured properly. It's actually easy, but not something most folks have seen before.
You want to secure the mill so that no matter which direction it wants to go, it's fighting a restraint. For starters, I like to run a chain with a binder across the base and use wood to protect the base. This keeps the mill on the deck so it can't bounce and shift. I then run 2" wide straps around the mill going to each corner of the trailer. Think of an X with the mill in the middle. It's important that the strap starts and ends at the same corner of the trailer, so RF corer, around the mill, back to the RF corner and repeat for each corner. Done this way, the mill has nowhere to go because it's always fighting a strap.
The most common error I've seen is people use two straps going to the back of the trailer corners, and only one going to the front corners. The thought is the threat is under braking, not acceleration. The problem with that is the front end of the mill can shift left or right, and as soon as that happens, one of the rear straps is loose. So if the front of the mill shifts two inches right, the right rear strap is now loose and bad things can happen.
I've got a couple of pics of what I'm talking about and will try to find them.