Hey everyone – thanks for all the great input!  I did the event this week, and it went stellar.
 
They ended up dropping the number of dogs they wanted from 400 to 250, and we increased them from 8:1 to 4:1 and kept the quote at the same price, so that worked out well.
 
I used a turkey fryer to heat up 40 dogs at a time, then we’d transfer them to the steam table and drop another pack of 40.  The school gave me a volunteer to help so I didn’t have to hire anyone, and I was able to rely on him to do the simple stuff (drop more dogs, hold the basket of dogs being transferred, check temps, take out trash, etc) and during the times when a line formed he’d wash up and jump in to help with condiments.
 
I used the large push-top ketchup and mustard, and threw in some relish as well to give a little more variety.  I chose for us to dress the dogs rather than self serve, to try and avoid there being a big mess.  The dressing of the dogs definitely slowed it down (and the relish took twice as long as the other two combined).  However, our line never got more than 4 or 5 deep, and since they were “free hot dogs” I didn’t worry so much about a short line forming.  Our turnaround time per dog was pretty quick (less than 20 seconds) when we were hustling.
 
We caught some sun, so I was able to lay the buns out on a table to self-steam.  I purchased them the day of the event so they were nice and fresh.
 
I should be getting some photos from the school photographer soon and will upload a pic of my rig and set up at the event.
 
The dogs were very well received.  I had four people come back to tell me that they were the best dogs they’ve ever had.  And that was with only three condiments. 🙂
 
Again, thanks everyone for all the good feedback and suggestions!  I really appreciate it.  I definitely learned a lot about the capacity and speed of my cart when the line forms.
 
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