Wait. A light integrator is likely to be an expensive piece of equipment attached to an expensive vacuum-frame/UV light source device.

So a UV "light meter," if it is cheap enough, and if used on a fairly clear, sunlit day with a glass frame...

This might be a reasonable system.

I would add a Stouffer step wedge to any system. With a step wedge, you can tie in the results of any try to the next attempt.