A mock up is an excellent idea and yes the steam locomotives I'm using are very heavy. My round house is from a kit and I have the floorplan on a full size paper template. I checked the instructions and there is no mention of the minimum distance from the door to the turntable. I was able to do a full size mockup using my longest locomotive and the dimensions of the turntable. It seemed like the turntable location was determined by the convergence of the tracks coming out of the roundhouse. I will be able to make sure it's "operational" before making the final decision. The door/lift bridge is only 16 inches wide in the plan because I don't know how to use SCARM yet. I plan on having a 40 inch truss bridge for the liftout.
If my turntable/roundhouse foot print is accurate on the plan, is the switch and short spur OK? Using Dave's rotated plan I could slide the whole footprint to the left at the top and move the switch further to the left on the outside oval.
