Well DagF your layout would work if I was just going to show a different way as to how things are done.
As in not better but different.
But the better approach is to go with a bigger project so everyone who wish’s can get involved at some level hands on.
OK if Johnny wants to do the layout whats needed is 3D space and then use box primitives to define player movement with in that space, just like your lay out. I'm sure this is done more or less the same in GTK.
Rayne as art director would decided the overall theme of the map and supply reference photos as to the modeling and texture requirements to maintain continuity.
If need be I'll do the layout set up.
The logic is all this will be referenced at 0 0 0 world space and and the box primitive used to define it's position relative to other buildings with in that space.
What I'll send back is a UrT asset temple that will compile a BSP map and Rayne would then take the labeling used and apply an art reference package. Now you can supply anyone using any 3d application a asset resource file containing a space reference and art references as to what to build with in that space.
There is one rule thought that all must abide by and that is just because you make it does not mean that it will be added to the project if it's not up to acceptable standards. (just saying)
Most of all have fun.