No Brainer..........Insulate.
I have a 40x40x17. Two 14' roll-ups (not insulated). Had it built last year.
I put 6 inch on the top (my roof is the galvanized), and 3 inch on the walls. Makes a HUGE difference. My weather is similar to yours. Gets as hot as 110F here. We had 31 days in a row over 100F last year. You can't even touch the walls on the outside of the building they get so hot. But inside will be 25 to 30 degrees cooler. Now by 5pm it will get pretty warm inside. Mainly because the doors aren't insulated. But it is at least manageable inside. In the mornings, it will make your nipples hard it gets so cold.
The roof dormers were a good idea as well. I did two, 14 footers. And I roll up both doors about 2 feet, and run a fan in each door, one blowing in, one blowing out. Makes a great breeze inside.
I am wondering, why would you do any 10 foot doors? Why not go 14? extra cost is minimal, and the doors will be more useful, especially if you sell your place sometime in the future.
Also, I watched them put up the insulation. Quite a job. I am glad someone else did that job.