The pilot was flying the airplane from the right seat as he practiced touch and go landings. He reported he had difficulty maintaining a stabilized approach, but elected to continue with the landing. The airplane porpoised during the landing, and the nose gear collapsed resulting in substantial damage to the fuselage and carry-through wing spar. The pilot stated he was not very experienced in flying from the right seat and he did not have access to the pitch trim which was located on the left seat yoke. In addition, the he stated he should have performed a go-around instead of continuing the landing.