When I did research for a story, I found no evidence of a remarkable modern toilet being installed anywhere in what was to become the state of Maine, let alone anywhere else in the country. Besides which, the "u" bend wasn't invented till the mid 1800's so, if Joshua had installed anything like a toilet (as it existed in 1767, or even 1795), anywhere near or attached to his house, the smell of sewage would have backed right into his house and grossed everyone out. What record about well-to-do houses have you come across that had working toilets attached to the house like you describe? Because boy, that would certainly change some of my research.

George Washington had an outhouse. So did Thomas Jefferson, and he was a guy who liked things to be modernized, so I don't think it was customary for anyone to have a toilet.  www.victoriancrapper.com states that "In fact, until iron foundries improved cast iron pipe and potteries improved terra cotta pipe in the 1800's, if there had been a functioning toilet, it would have been placed in the outhouse anyway." (Which makes it an outhouse, not an indoor toilet.)

  You're on a roll today!