Hey, I think that you already have a plan, and it sounds like a good one. Everythng I have heard about the Trent Serern is that it is better to do in a houseboat than a sailboat. Interesting physics though so whatever you decide could be great.
I met a couple a few years ago whose plan was to visit every marina and anchorage on Lake Huron and Lake Michigan, and then to go from there. They were a Florida couple who did as you plan and rented their home for the summer (Florida, but still) and lived on a 36'Chris Craft all summer. They used it like a trawler to keep fuel costs down and at the end of each summer their costs were not to bad considering what they wanted. They also hop scotched a car as they found local transit a fine way to go back and get the car and then they could explore local areas at their whim with less cost.
I met them on their first summer and they had done the
West shore of Huron and were working their way South in Michigan. Having done the Bays at the tip of Michigan the boat wintered at a good yard in Northport and away they went in the Spring. They thought that they would make Chicago or Wisconsin the following year. Thought it was a great idea. Hope you get to your relatives!