Hey Kevin & Dave,
Dave's designs are awe inspiring and vey cool and interesting.
My personal preference would be to have the turntable located in one of your orginal designed dog bones. Or have the TT off the layout sort of Norm Charboneau all by itself so you could walk around it, but I do not know if this is possible in your space. Daves newer design has further reaches so you will need to crawl under the layout and put access hatches into the layout once it's built. 8'+ deep is a long reach. If that works for you go for it.
Your orginal Dog bones design with its 2' walk around at 7' deep is "reachable" to the middle, IMO. I'm just not into access hatches, duckunders etc at 50 years old my back aches thinking about it. My rambling done, it's not what's best for me but what's best for you! Keep us posted.
