I have painted several cars and truck outdoors and the biggest problem is airborne debris and insects. Pick a day when the wind is light and that will cut down on the little floaters that tend to end up in the paint job. Not much you can do about the bugs except hope they will stay away. If one does get in the paint don't try to pick it out, that usually only makes it worse. Wait until the paint dries and then remove it carefully. If you are using a base coat/ clear coat system, get them out after the base coat has dried and then spray the clear. Since you will be under a carport that will help a lot. If you want to close the sides you could use plastic sheeting or tarps but you will need a fan to help exhaust the fumes. Painting outdoors can be done, just realize that you will not have a show truck finish. If you do all the prep work and take as many precautions as possible, a quality job is obtainable. Check out the link to my "70 C10, it was painted outdoors under a tarp I had suspended from poles at each corner. Hope this helps a little.
