We align the doors then drill a couple of 1/8" holes through the hinges. That way you can insert a drill bit to line the hinges easily. I agree, add weight and weather strips as it all affects fit. Glue on weather strips can be taped in place for testing. It depends how picky you want to get. We prefit every thing. Hood inserts,door handles,window moldings,tail lights,headlight bezels,etc. You never know what doesn't fit. painting can be done with doors on or off. A less experienced painter may have better results with all the body parts attached.
Good Luck Doug