Craig,
You may want to stop by
Holman's in Tempe. They ahve a number of high viz vests and you can get you hands on them and see how small they can pack down to.
In my BOB I carry a Blaze Orange boonie cap I purchased from Cabela's (which they only seem to have in Gore Tex or in cold weather version now!). Not quite as much orange material but it is a truely dual use item. Come to think of it, if you wait a few days you could go to our new Cabela's and see what they have <img src="/images/graemlins/laugh.gif" alt="" />
Although, Holman's has some nice vests with pockets that may be useful in a SHTF situation.