hip roof with gable dormer ventilation

I have a 12:12 hip roof on a 30X50 victorian balloon framed house in Western Montana, with 2 gable end dormers. The balloon framing runs 3'-8" into 2nd floor, then hip or gable end starts up to 9' ceiling. This is all insulated (walls, hip roof and gable roof up to ceiling, which is also insulated. The roof is 15' to the main ridge (20' long) and the gable dormers are around 8' tall (above balloon frame). I have ridge venting in the gable ends and main ridge but can't add soffit vents because of insulation in minimal 2X6 roof structure. (and winter is longer than summer here...) I also have apartments upstairs so only the hallway and stairwell could provide air to the attic, although there is no vent now. I also live on a corner in a historic property where all roof planes are visible from a street, so a mechanical ridge fan is undesirable.
What is the best way to cool this attic in summer, and retain my warranty for 40 year roof I had put on a few years ago?

 

fearless,

Best to contact a good roofing company to evaluate what you have and what can be done. This requires a visual by a professional.

Good Luck!