Do you want these ai meshed? I'm presuming not, because of the size you asked for?
Id also second the idea for using Blitz Craigs maps as well. His maps are very good and already donated to the community. Ive based a few maps on these for our Man vs Bots server, with a lot of alteration for our game mode. I asked and received permission from him to do that first. But I think for what you have in mind you wouldn't need that many changes. If you've got a more detailed brief of what you need, and you don't need ai meshing, I can adapt a few for you if you want.