20 years in submarines Alex so I know you can work without natural light lol, I just find that a lot of what I do is better under natural light & although you may get light in there will be a lot of dark areas, I know from the unit I have. Like you say get it up & start working & then make what improvements you need as an when you need them. How you have things planned for the inside will also make a difference, wouldn't count on leaving the door open very often where we live lol.