frost on tomatoes

Ok, Minneapolis is supposed to get frost tonite. I still have lots of green and turning tomatoes in my garden. U of M suggests harvesting all, and ripening inside as they say it is not good to do canning with frost exposed fruit. i have been making tons of salsa. Other folks I have heard throw a sheet over them and keep going? Any opinions, experience here would be helpful. wont the cool weather slow down ripening outside a ton too? Thanks, Hill

I would cover with a blanket then remove when the sun can warm them up. Grew up north of Bemidji, but now solidly in Texas - once kept a tom plant through several freezes by wrapping in a blanket - finally had a freeze that lasted more than 24 hours and lost it.