I went by myself this year, so I pulled out the speedster. A friend joined me later in his 1926 T. It was a little hot, but good food, friends and drinks made it fun.
I did not get any pictures of some of the young boys, but they thought that since the speedster had no doors, they were free to get in and I saw at least six or more do so. I had the key out and the starter switch is hidden under the dash, so they did not get in any trouble. I am glad they had fun, that is what the picnic was all about.
WOW l had to look twice at that photo of the building, its almost identical to one no more that 30 mins T drive from my place.. the pickups give the origin away....
Willie - I only let people sit in my cars when I am there, and let them do it them often.
If I had a speedster like yours and had to leave, I'd at least stretch masking tape across the door openings so people would get the message not to sit in or climb on it.
Just my opinion, your mileage may vary.