Comment by DonnyV
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.
If you are using a 3d engine that doesn't support actual isometric views, you can put the "iso" in isometric by moving the camera far away and at the same time zooming in on the object. This has the effect that all points of the object have roughly the same distance from the camera (compared to the huge distance you moved the camera away), so there is no perspective "shortening" of points farther away. This is especially important if you have rectangular wall segments that must fit together.