Since you are looking for suggestions, I thought I'd just give it a go.
Although i really like the asymmetry in this map, I think having the outposts and expansion points more symmetrical would benefit the gameplay of the map.
For example: You have an outpost on the right side but none on the left side.
What I would also suggest is having more settlements in total. In your case the players each have only 2 settlements each, which may cause quite a slow game, since the player wont generate a lot of money.
Design-wise the map is already in a good condition, but I would suggest adding a few rocks and dead trees (although it doesnt make a lot of sense), as well as some different but similiar textures.(I think you were gonna do that anyway
) If you have trouble finding fitting textures or objects, like I had in the beginning, try to look at maps that already exist and study the way they are textured.
Looking forward to updates.