Welcome to the forum. Zone 7 is similar to my zone. Black tubes will be much too hot during July and August. Don't use them as is.
What to do? If you had a soldering iron, you could burn some holes in the tubes to vent them as Dogdoc suggested. We don't want large holes, we want small holes that will allow hot air out and air into the tube.
I would go to a paint store and get their thoughts on what spray paint will work on them. White is what I would attempt to paint them. It might take two coats. Painting them can't reduce our ventilation - so if painting them means I have go back and add vent holes then I would do so.
One other thing you can do, split the tubes down one side top to bottom and use cable ties to make two tubes into one tube. You will almost double the outside size. This will help with managing air in and air out. If you ever direct seed an acorn or chestnut, you can take a 5 ft tall black tube and cut it into three 20 inch tubes.
My main point - a black tube will fry your seedlings in July and August if you use as is. Modify in some way or discard them.
Good luck with your fruit trees and welcome to this forum. Glad to have you.
Wayne