Are the edges of the vynl mat laying flat? It appears so.
I'm probably not part of your market, but I'm interested to see how an outdoor mat turns out, such as the forested one you mentioned. Perhaps hills or mountains would also be worthwhile.
The various, yet integrated colors of the tomb rooms and the organic, rounded feel of the debris were a nice counter to the regularity of the square-gridded layout. I hope the dungeon finishes off as successfully.