I hesitate to give specific advice from so far away, but my experience of music promoters is that they are some of the most entrepreneurial people out there (to the point that they will exploit you if allowed, of course). Offhand, I would look for ways to get income from the venues, whose economics are simple: book bands with fans, sell booze to fans, profit. They're much more likely to spend, and to understand their own economics than bands themselves. Start your research by calling around local and regional papers as if you had a pub or something and wanted to take out your own advertising - get the rate card of old-media publications and try to guess how much it costs a venue owner to bring the public inside the door and spending money. Or again, simply ask them.

The more I think about it, the more I think venues are your revenue stream. Bands come and go, whereas stages tend to stay in one place :-)