The Dirtworx swing out is pretty easy to remove. You might be able to use this idea if you build your own.
He put a bolt at the top of the pivot pin, that holds the swing-out on. All you'd have to do is remove that bolt, then lift off the tire carrier. You'd probably want to put something back on the pivot to protect it from rust. I've actually been toying with that idea myself. A piece of PVC pipe would suffice, then just put the bolt back in.
Here's the pivot point:
And here's the swivel part of the swing out:
In that last pic, you can see the recess for the big washer on the bolt.
Hope this helps some. Please post up pics if you build
EDIT: Didn't notice that this thread is 2 months old. Oh well, lol!