The problem is that in bright sun, the iris contracts and does not dilate quickly when the vf is brought up to the eye.

With the EVF? The eye cup is designed to block out light. Some people who wear glasses find they can't block it out to their satisfaction, but there are aftermarket oversized eye cups that are supposed to be an improvement. They would probably help even if you don't wear glasses. I've never used one so can't recommend a specific product. 

Any tips re shooting with a bright sun at your back? I can't see the settings at the bottom of the vf or flash.