It can be done, however you would loose the ease of cutting that goes with the buggy barn patterns. If I were to do that, I myself would cut the entire thing as templates then cut maybe four layers of fabric.
If you are looking to use only two fabrics ... have you thought about cutting 10" squares out of two fabrics then have one star the reverse of the other? You would still have only two fabrics but the cutting and assembly would be much easier - imho.