I am looking to sell at a Model Railroad Show.
The promoters have told me that last year's attendance was 3000-3500 adults plus 2000 kids under 12.
(I am thinking a lot of grampa's bringing their grand kids... but just a guess.)
I plan on having youth sized shirts in this design:

And two adult shirts (in sizes S thru 2XL):
and
I am looking for suggestions for...
1. Number of total shirts to bring?
2. Size allocation?
I have another train show I can attend in May... so if I overestimate, I just have to store the extras for several months. (I am not printing at the show, so it's a "print before you go" situation.)
This will be my first crack at selling at a show, so any help would be appreciated.
Thanks,
Brett