I really appreciate all the advice and recommendations: this forum is a fantastic resource because you get a variety of perspectives and good ideas, so quickly: Thank you.
Good or bad, I'm not going to remove the old carpet in my trainroom: one can do anything if willing to pay the price but it's not worth the hassle. On the other hand, I can remove the carpet in my workshop, which is where carpet is really unfeasible.
Trainroom: see the diagram further below: the gray areas are the only areas I need to cover: my two aisles,are 24 - 36 inches wide, and my stairs 36". Note that everything north of the top aisle in the picture is a shelf benchtop over cabinets, so there is no carpet under that. And I won't carpet under the layout island, which has skirts all around and is storage for all my empty boxes, etc. I think will use Apache Mills 36" industrial carpet runner (below), cut to fit and, nailed down with moldings as wall to wall on all edges. The old carpet will essentially be a thick pad for this new.
Workshop: I will remove the old carpet and install rubber workshop/garage tiles.The bathroom has linoleum tiles and is in good shape.
I figure I need 200 sq. ft of carpet runner and about 80 sq feet of rubber tiles for the workshop. At $2.60 and $3.00 per square foot respectively the project will cost about what a good Legacy loco costs . . . I'l start saving now and will probably do it over the holidays.