Bob, aka DAD, the lower level foam I am thinking of just a retaining wall, and the upper level I am going to add one more layer of 4" then a 2" top over everything. That way I get to tunnels and no trains running on the airfield!
Johan, thanks the scenery is going to be tough for me as sometimes I have a hard time envisioning things! But I will do what I can and keep posting as I go along!
Mark, Chris A. helped me with the supports on the lower level and it has not legs and I really like that! So I was trying to keep it that way!