Thank you for all the replies. I probably should have asked more specifically, what is the longest amount of time you've spent in your TC, but distance question is also interesting question that brings up other questions about truck maintenance with the wear and tear of a very long trip.
The reason I asked the question is that I'm planning on taking a year off with my family and traveling the US and Canada in our TC. My two young daughters would be home schooled (or camper schooled) during that year. I'm probably completely crazy to try and get a family of 4 to live together in a TC for that long, but my family is on board with the plan and I wanted to give it a go while my daughters are still young.