I would consider venting the top ridge or the back wall very high up with a pusher fan to exhaust the hot air.
Then consider a simple foam board insulation above your rafter truss bar.... that then you could put some more insulation on top. you dont hav emuch space to work with.
Does anyone...
In My Opinion- by the roof picture of your garage- that kickdown part of your cieling is going to restrict the height the car can be lifted to to a maximum - and then lower than that is your garage door track and hangers. So with an open garage door- the car could onlygo UP so far without...