Where's DirtDawg when you need him?
He had a design for a midbass horn that sounded like a great way to get a lot of sound out of a smaller system. It used two 12" pro woofers mounted similar to the WO-32 and facing each other with a divider board between them that made the centerline of a horn made with bent plywood sides. Put two-inch drivers with some nice cast aluminum horns for high frequency (1,500 hz and up perhaps) and save the bottom couple hundred hz for some subs. You might do better with a pair of 18" drivers in a big bass reflex box for subs, or go for a pair of Imperials. Something like Labsubs would be overkill (since they're designed to be run four to a side).
The point here is to have the midbass horns, which are similar in size and shape to a WO, do the bulk of the work as far as voice is concerned. The boxes wouldn't be that expensive to build and you can power them with smallish amps since they're super efficient. You'd get deep and powerful voice with no boominess and your subs could still crank out substantial bass for music without having to handle voice.
I think serious PA is a lot to ask of a two way system although Jim might disagree.
If I were in your position, I'd come up with two or three possible options for system designs and then hire a professional sound person to come by and give some advice. Spending a couple hundred on an experienced pro could save you many thousands down the road. And who knows, maybe you'd teach your pro a thing or two. Maybe they'd even offer you a job.

One more thing, take a close look at those existing compression drivers up on the poles. Some of those old football stadium horns have major 2" Electrovoice or Altec drivers on them. Shine them up and add some new horns, crossovers and amps and they'll sound great for another 20 years. There's your tweeters.
Good luck!