TinaBaby,
I think that you're going to have to separate the two, or tie the younger horse up while the older horse eats.
However, if you want to try and resolve this, my best suggestion would be to assert your own dominance in this situation. Let the younger guy know that the feed bowls are *yours,* not his, if he tries to run the older horse off, run him off instead, being very careful to show no aggression towards the older horse. If you need to, carry a whip or lead rope to smack the younger horse with, but pet and love on the older horse. Be *very* careful about ending up in the middle of a nipping fight, don't allow the younger horse near you when you are rewarding the older horse.
When I work with my horse being aggressive or pushy about feed I stomp, twist my hips as though to kick, or (as ridiculous as it sounds) bare my teeth, and Sham backs off from the feed till I turn away (as AQHA Breeder was saying, "take the pressure off"). I've "bitten" my horse before though (sneaking my hand up to pinch so he doesn't realize that I didn't actually close my mouth on his coat) and he does respect my mouth and space.
Like I said at the beginning though, it sounds like you'll need to separate the two for feedings, unless you plan on standing out there every feeding for awhile. Even then, when you leave the two alone again, the picking is likely to continue. The lady who boards my horse while I'm out of state at school has to separate him from all the other horses at feeding time because he simply will not let the other horses eat.
Just something to consider.
Snuffy:
For trailering, I would try to get a divider between the two horses, keeping Smurf's face/hind away from the other horses as much as possible.
It is also possible that Smurf will have no problems trailering with the other horses as long as you aren't around (Up in the cab). See if you can load them in the trailer (Smurf last so he doesn't feel ignored), then leave for awhile (find a place to watch where they won't see/hear you). When you return, unload Smurf first and put him aside so you can take out the second horse.
Make sure you hang out close enough that if a problem develops you can step in and intervene before something dangerous happens, being willing to let them get a squeal or two out of the way and see if things settle down (I'm sure you know the difference between a "Leave me alone" and "I'm going to kill you!" action!

). Other than that, I like AQHA Breeder's suggestion! Let us know that that works for y'all!
~*Naira*~