I started building an iso game a couple years ago and like you was not looking forward to having to make so much art. Then I had an idea. Build it in a 3D engine and lock the camera in an iso like position. Now I can use 3d models and not have to worry about creating all these different views. Also you could do effects when walking around the board by spinning the camera and then locking it in a different iso position. I'm pretty sure this is how newer iso games are made.