Hi Peter
(Finally, I can help!! First time for me!)
I have Atlas track with Flexxbed from Hobby Innovations, somewhat similar to what you have. I did not use the "feet" from the corral, but folded them up (you could remove them). I then put a 1/4" piece of styrofoam (a sheet I cut from some packing) and slid it underneath the corral. Then I placed the corral by trial and error at the right distance. It continues to work well after 2 years.
One tip: I wound up buying a separate accessory transformer to run the corral, because I had to have the voltage a bit different than other accessories (ice house, milk car, etc.). The corral is real touchy; some of the horses get rambunctious and fall over if the voltage isn't right.
Sorry no pics readily available; I can see if I can dig one out of "the archives" if you would like.
Bruce