Ken- l love the creative process you're going through. Thanks for sharing with us.
A few thoughts- keep the run around tracks and sidings. You can't have too many in my opinion.
Can you shift the bridges to the left and just use module 5 as a swing out instead of both?
I bought a great telescoping attic ladder from Werner several years back. It's more compact than a traditional type and works great.
I think the two car garage idea with the trains upstairs may be a winner (assuming you need a garage too).
I would look at conventional construction over a kit as well. Talk to some local contractors for their thoughts.
Thanks Bob! Your point on the run-around tracks is good. Now that I have allowed my space to expand to 14x24, I could put those back in and crowd the operating space a few inches. I may do that. Not sure what you mean about a swing module rather than slide out: that implies that the end by the bridges is a fixed pivot (right?), and that the module joints is a curve (hard to get perfect). I will think about some more, I may be missing your point.
I had mentioned the above a garage idea earlier in discussions with Mary (wife, who organizes "train vacations" for me), and she was interested. Have not yet brought up the idea again, but did spend some time looking at double-car garages on the internet yesterday - 24x24 seems to be about the minimal practical size.
Thanks on the ladder idea, cool!