Re:Enclosed hot dog trailer
I have an 8' x 14', and it has more room than I need. We usually have 2 people working, but ocasionally have 3. It also depends on how much room your sinks take up. I have a Freezer on the back wall, and the hand sink and triple sink all have bowls about the size of a drop in bar sink and are on the front wall. If you didn't need the freezer (and I really don't, but it was in the trailer when I got it) and used smaller sinks, you wouldn't need as much room.
I don't think I would get any smaller than 7' x 10' for 2 people though.