Spoke with my decal cutter about this subject this afternoon. I plan to take him some designs this week. He was also in the military - Army. I told him what you were wanting and he can certainly do them. The key is keeping things to 1 or 2 colors... and the simpler the better.
HOWEVER... he can also get stuff screen printed, which makes them multi-color and they can be quite complex. But, the price goes up quite a bit 'cause he has to send them off to be done.
So... I'm going to take some of the basic designs described in this thread and see what we can come up with. If you have ideas, I can factor this into the design.
As for single custom decals... I can get them made there too for a good price - just let me know what you're wanting and I can get you a quote - just tell me what, size, and color.