Well, for another opinion, I like that you included the roads and trails - but it does 'hard wire' them into your gaming options. As to getting a bigger piece with a shorter knap, that does seem to be a challenge these days, been years since I found much in the way of shorter knap fake fur - though I did find one piece in a very dark brown that I've yet to work on. However, a good yardage/fabric shop should be able to find some for you and order it up in whatever length you need, width will be limited, usually the widest is 54" (at least in USA).
As to coloring, I actually like what you did and I wouldn't get so squirmy about minor color mismatches at the edges, nature is remarkably variegated. Your mat looks orders of magnitude better than 90% of the mats I've seen over the decades.
One thing you can give a shot at doing with the current mat setup - use some latex caulk to build (away from the mats!) a river to go where the widest road sits. It will take some careful measuring to get it right but it will allow a very different game experience with a river in place of the road - and take away the river to return to the road. Be sure and paint both sides of the latex once cured or it will remain 'sticky' for a long time. I'd make a template to work with. If you can, lay the latex caulk on a piece of flat, clean glass - template under the glass. This gives a nice uniform bottom to the piece(s) and is easy to peel up and clean up for the next piece.
Not sure, but it looks like you started with a green. If so, if you can start with a straw yellowish color you might get better results.
But your results are pretty darn good as it stands.