Nuke,
It sounds like you are doing exactly what I plan on doing in a few years, having three m80's behind an acoustically transparent screen. Of course you want to make sure that the entire speaker is behind the screen so that any colorations from the screen would be equal to all 3 speakers and drivers of each speaker. I imagined that I would have to put them on a speaker stand up-side-down to get the tweeters closer to ear level. But you said that the bottom of the screen is only 15" off of the ground so I guess that you don't need to do this.
Anyway, I am currently using Dayton SSHM-18 18" High Mass Metal Speaker Stands for my M22's (There is also a 12" and 24" stand in this model). These can be found at partsexpress.com and are only about $100. You can mass load these stands for extra stability, but they are very stable for my setup without doing that since they are already quite heavy. You probably would want to mass load them with the m80's though. Let us know how it turns out, I am anxious to hear since I am planning on a similar setup in the future.
- Nick
