How to insulate cathedral ceiling in detached garage - Zone 2A

I have a detached garage I'm looking to insulate and turn into an office/workshop - here are the details:
- Zone 2A (hot and humid)
- Ridge vent but no soffit vents
- Plan to cool with mini-split
- 2x4 framing on walls, 2x6 in roof

I'm trying to keep costs down where possible so was hoping to do most as DIY. My questions:
- Can I use bats/foam board in the roof without any lower/soffit venting? There are so many conflicting answers, and most discussions seem to relate to heating spaces in cold climates (not cooling in hot). With the climate control of the mini-split, what are the considerations about moisture accumulation?
- A lot of people seem to recommend spray-foaming the roof, but being on the Gulf Coast I have concerns about roof damage from hurricanes/weather events and being unable to make repairs if it's all bonded to foam...

My current plan for the walls is to use batts and then dry-wall with utilities on the exterior in conduit (easier for me to achieve DIY), use the foam boards in the door, cut and frame a 'regular' access door in one wall to limit how often I open the double roller door. The roof is killing me with trying to figure out the best option!