Tom, Thank you. I used Homasote with cork to build up a roadbed back in my HO days, so figured I would do the same in O gauge. I've been in O since 2012, but this is the first I am really building benchwork and realistic scenery like in HO. I got all this old Homasote from in my mother-in-law's basement. The lady she bought from was a seamstress and had a 4 x 10 sheet of Homasote on top of her work table. The whole thing was measured off in 1" apart parallel lines. There were lots of pinholes in it, but I only found one pin jabbed in sideways. I got the O gauge cork from a local Forum member. Met him at the Sheetz convenience store a mile away.
I don't know why Super O didn't stick on the market. The track looks great!! I'll be glad to see what you are doing someday.