Joy!!
I would go for the grassed area with a good concrete footing. The paved area may be appealing now for its apparent simplicity, but I think you will soon find the pier will be in the way down there. Your pavers, though large, won't have suitable footprint or mass for bolting to directly.
My own pier is on a ~360kg block of concrete which is probably considered on the small side, but is adequate for the small scopes and short focal lengths I work with.