Outdoor Brewing and UV?

I've got 16 AG batches under my belt but I started last fall and have been doing them all inside (on a gas range, takes awhile but is ok). Today it's finally nice enough to brew outside.

I know skunkiness comes from MBT which comes from isomerized alpha acids. Is that an issue during the boil or does it only become an issue post boil. Alot of pictures have guys with their brewpot in full sun so I'm thinking it's not an issue but just checking.

Rudeboy

I can't seem to put my finger on my source, but I have read that skunking requires both isomerized acids AND some products of the fermentation process (riboflavin comes to mind, but I can't verify this). The collective experience of homebrewers seems to also support the idea that plain wort alone does not skunk quickly, as evidenced by so many brewers who boil in direct sunlight on their deck, patio, etc. and/or rack to glass carboys in the sunlight.