I doubt compleyely that the 1" Foam would be any good to support track unless you had supports every 6"-1ft even at a foot I think it would be too weak for the job. Said this before I think but my build link below will give you ideas.Hi Fred-
Yes, I do know Dan and he's pretty much responsible for bringing me over to the "dark side". Actually I'm going to see him in a few minutes as he's only 10 minutes away. I've visited his layout several times and have met some of the guys so possibly we've met as well (I'm not great remembering names).
Thanks for your replies, I appreciate all the help I can get.
Another way is to use building block shaped like an 8 to gain height mounted on Concrete Girders/Gravel Boards with similar Girders for the track base. Not the cheepest solution but quick to assemble. Nick Trudgeon who built the Southern Cross Garden Railway uses this method. Book well worth a read if you can get it or borrow it. He describes these methods in his book.