"Would it be worthwhile to do something like trade in my spiffy Toyota for some beat up old car you can fix with a wrench, spare wires and chewing gum? Are there other such near-to-home projects I could take up that would be easily transferable to cruising life and forcing me to be more self sufficient? I guess the trailer sailor makes the most sense. I don't know why, for some reason, I feel hesitation about that... none of those boats really speak to me, and the ones that do would be too heavy for lake sailing."
I wouldn't trade cars. The time you spend on a clunker isn't going to add to your knowledge base for cruising. But here is a project that is directly relevant: build a dinghy. Plans are plentiful, some are even free, the process of building will teach you much (about fiberglass, epoxy resin, discipline and determination). And, of course, in the end you'll have an item that you can take cruising.