This is just throwing numbers out but I am thinking 50x50m or 100m area for the main base might be about right. Certianly not any larger and perhaps smaller due to the amount of people that have so far acknowledged their participation. And it may work out that we only have one actual team of builders that end up needing to build both bases?

We don't want to bite off more than can be accomplished by a small team if we want to finish in a resonable amount of time.

As soon as it is decided can we get your max LxWXH for the base? That would help us start to envision what we might build.