Addendum to above. Sorry if I seem sarcastic. It's more like I can't follow your reasoning which my be my 67 yr old brain not functioning. Your ceiling does, to me, look 12 ft high, no ? I don't get why not just make a narrow shelf layout, single main and a few spurs, loading dock/depot, light scenery at say, 52" common MRR height. What's the need for it near ceiling in the first place ? How much room would it take up if shelf were same width as you have now (+-) but at eye level ?