Kevin,
I understand your situation, but you've gone from Technomad boxes to in-ground 'mushrooms', could it even turn out that paging horns might be appropriate? An NDA or CDA may prevent you from discussing the particulars of the project but I don't think it will prevent you from addressing products or applications in general. Asking something like "who offers this type of speaker" or "who makes a weatherproof speaker with the following characteristics" is probably not going to violate a NDA. So maybe you can provide some more information without tying it to any specific project or use.
As far as commercial 'mushroom' speakers, I know of Atlas Sound, Bose, OWI, Rockustics, Soundtube and TIC.