Smallest mapsize that still spawns in the Launch Site?

What is the smallest possible map that still spawns in the launch site?

I had a server with 3000 mapsize and that one didn't spawn in the Launch Site. But now I have set it to 3500 and that does spawn in the Launch Site but unfortunately it's a bit too big for my 50 players max server.

 

Size: 3000
Seed: 4, 20, 42, 60
Size: 2600
Seed: 777, 2239341

they have a launch site

you can also look here Rust Live Map & Map Generator for mapseeds

 

Sometimes you have a launch site in a small map but then other stuff is missing.

Is there any way to select which monuments to spawn? I advertise scientists in the millitary tunnels but now I dont have millitary tunnels. But my server isnt that active that I can have a big map.