We drive up to fish in Ontario each summer, and Jungseeds fishing resort would be about 160+ miles further north in a straight shot from me. I would have to agree that it would be very difficult to get the larger tomatoes ripe there, since I think I am at about the northern limit for pushing success right here. Our day and night temps run maybe 5 degrees warmer here, and I suspect the night temps are affected by that big body of cold water the resort is on into July. Maybe if the toms were started very early, potted up into successively larger containers without getting too rootbound, and then grown under some kind of plastic cover, either high tunnels or just some simple lathe and plastic removable panels that can be wired together to create a heat trap. Growing close to a sunny south facing house wall would also speed things up. Growing in large pots or plastic tubs would help with soil temps. You can get quite creative with plastic lean-to's or simple tents, keeping ventilation in mind for hot and sunny days. I definitely would grow a couple of earlies like Stupice or Aurora just to make sure of some ripe tomatos to enjoy. Unless we have an unusually sunny hot summer, I don't think the larger heirlooms can ripen without some help from plastic sheeting that far north.
