I'm only a semi-regular but what I'd suggest is for the group to aim for one of the slightly more separate areas of parking lot, rather than the "prime spots" right in front of the coffee house - these tend to get taken very early by the stuff people really want to see (and / or the people who really want to be seen ...), so it would be bad form to try to block off a group of them.
Here's a pic of the parking lot(s). I've marked in green the areas where I've seen single-marque groups congregate before - we could aim for one of those, depending on how many we expect. Top right might be best, followed by bottom right.
View attachment 18618