I used to get "naked at noon" in NH and TN until they built a new house almost right in my face, and now I don't think I'm going to be able to swing that any more here unless I put up a high fence. I would do 10 to 13 minutes on each side in full, mid day Sun. I'd never burn. This year I'm going to have to wear my short shorts but that should still get me quite a bit of Vit D. Some days I'd ride my bicycle to the nearby park in short shorts and sit on the empty bleachers for 20 minutes or so and absorb sun. I never use sunscreen these days and never used it much at all anyway.
My NMD put me on 2000 IU of D3 daily but I quit that when I went on this program. Hopefully I'll be fine on this program and won't have/need to chase NMDs around for tests, etc. :)