Food for thought, what if they have the main backstage gate next to FFL and Gringotts have it be as if it's a Tall tunnel, and then for the side facing MIB, being just city building facades?
Something like this perhaps (and for ride building size, about 1.64 Acres.
View attachment 6517
Light Blue: Lagoon Extension
Light Yellow: Extension of the London Waterfront Walls
Light Green: New forestry/shrubbery added in
Light Grey: Repaved and reconfigured Pathway
Dark Purple: London Waterfront Facades
Dark Violet: New Themed Backstage gate as a facade
Orange: MoM (1.64 Acres)