BC, Not too far from me is Snowline Sports Snowline Sports
Check out the pic of their track inventory. I will be checking with them, before winter to see what they have.
Also another source is conveyor belt manufacturers, many have very interesting patterns, some with raised chevron style patterns that swim. The only downsize is most don't have lateral stiffeners and flex (curl) up outside the tire width. But if you install lateral cleats they should work out OK.
I've sourced out one company that makes what I want but you need to buy it in 100 ft. rolls, so maybe a couple of us guys will work together and split the costs. I will update this thread as the fall approaches.