Hi Doug,
We've made short scale Epics, and I can't forsee any problems with making a 28 scale baritone guitar with the Epic body shape (we make them in the Orion shape regularly).
Usefulness? I feel the baritone is the ultimate rhythm guitar. It's also a natural for composition, working on bass lines and leads as you need to. The throaty sound is also excellent for blues.
To emphasize the interesting bassiness of a bari, I'd suggest Coco Bolo for the top. It will preserve the highs and keep the lows nice and large. Mahogany for the body will keep the most versatility. Consider the kinds of sounds you expect from the guitar, and we can suggest some wood combinations to make it the natural sound of the guitar.