Update - Roofer showed up yesterday and suggested "O'hagin" vents - basically fake roof tiles so you don't have a big T-Top or dome sticking out of the roof.

Another HVAC guy came and took measurements, talked about the goals, looked at supply vent location, etc and is going to get back to me (I have more confidence in this guy - seemed to care, take the time to check everything out, and do some math w/product matching). Told him about the roof and he suggested adding a couple more vents just to ventilate the attic space above the room, making it easier to cool.

Roofer had a hole in his schedule and shows up tomorrow.