My first charter was a GB 32, single screw, done in the San Juan Islands of WA. We had a great time. I don't understand what your hesitation is to chartering a single screw boat. It's a good way to learn about trawlers, chartering and the cruise the North Channel area.
I cruised the North Channel and Georgian Bay in the mid-60's and I think that would be a great place to spend some time on a single screw boat.
If that's what's available and you want to go cruising, I'd jump on it, make the reservations and just do it. You'll never look back on it and be happy that you only had a single screw boat.
Mike and Tina
2008 Monaco Camelot 350hp Cummins
1981 Boston Whaler 13'