By adding one more tile the 8x6 is fully filled. Inverse of the new tile also may be added instead. (Possibly both may be added to 7x7 version, but it is not straight forward). Nontheless, thanks for great job. Your image inspired me to rethink tiling - but, for now I will use 16 tiles version (scheme attached, no "roads", less data and easier to automate in-game generation/editing).