Oh, dear, I realize that you have not visited this forum since June but I do hope you return!
Hello from a fellow Michigander with a narrowboat fascination.
I've had the same stumbling block... re: hire companies do not want to rent to single handlers. And I'm not really interested in a hotel boat, I prefer the "real" experience, warts and all.
Luckily for me, I had an English mother so I am eligible for citizenship by descent. I therefore do not have to contend with limitations on the length of any trip I may take to the UK. I've even considered retiring there in a few years...