Potty training

I figured it's about to start potty training Troy. The weather was great over the weekend (for Norway). I pretty much let Troy run around without any clothes on, and told him that it was OK to pee outside and that he would have to use the toilet inside. He enjoyed the freedom, and was so proud when he used the toilet. The peeing went well, he stayed dry the entire weekend, but the pooping wasn't such a success. I spent the weekend at my sister's, and yesterday Celina came runing outside, telling me that Troy was pooping on the chair. One thing is changing a diaper, cleaning it off a chair is something else. Today Troy was in the bathtub, and when I went in to check on him, he held on to the changing table, with his butt hanging over the bath tub, using it as a toilet. He was so proud of himself for coming up with this solution, so what could I do.