BJ did well this year (2nd) with maybe 50 active participants, including a core group of 15-20 who pulled an all-nighter at some point or completed the road trip. Plus some who wandered by and completed an easy 3-point item here or there. The list was ~240 items (plus road trip stuff), which is very doable for that number of people - though nobody has ever finished the entire list. Our completion rate was about 90% IIRC. So Scav is a slightly more niche activity than you’d think, and the barrier to contention isn’t too high.
That said, the Evil Empire won again, so maybe we should borrow a page from the Snitchcock/L. Ron Hubbard playbook of universal participation.