When using jig trailers do you thread the hook through the trailer like you would do on a twistertail and jighead or do you simply hook it right through without sliding any of the plastic up onto the shank of the hook

onto the shank, but I try variations when needed...

depends on how big of a profile you want it to be!

I thread it on to the shank of the hook. I have done it both ways but like the threaded way better for pitching. When you nose hook a trailer sometimes it will swing around and catch the claw part of the trailer on the hook.
I mostly use Lake Fork Tackle pig claws, and craw tubes, Baby Paca Craws and Zoom vibra speed craw.

I thread mine on and I put a drop of super glue on the shank of the hook and then push it over the barb. This keeps the trailer in place and you don't go through as many trailers.

Quoted for emphasis

for instance, if I feel like they are feeding on bluegill I like to thread it on there, but if I think they are feeding on big crawfish, I like to hang a big chunk off the back...Either way will work, just find out what you like best

Another reason to peg it up on the keeper is for skipping. It compacts the bait profile and creates less resistance. You can skip it up under docks better if you thread the trailer.

*cues Saturday morning cartoon's the More you Know theme song*

If it is a chunk style I just put the hook through it. For a trailer that has a body to it I thread it up the hook.

thanks for the info guys

Same as above, for big profile hook it thru the front part of the bait. Never had to worm it on the hook. Big bait = big fish!!