I have a hard time growing a single large tomato in the field that actually tastes good (so I’m not picky with the field tomatoes), so I was wondering how you can @Greenstorm, but I found this weather graph with more accurate temps to my field by the ocean. My September average high is 58F/14C, and Ft St James is 71F/21C. But wow your summer night time temps are so low! And obviously my season is waayy longer.
I found the promiscous tomatoes to taste better in my temps/have an easier time setting fruit, but be more susceptible to blight than many of the heirlooms. In 2022 there was 100% mortality with promiscous ones, so obviously that’s a giant problem 
Very excited to try some of @WilliamGrowsTomatoes and see how those do.
Back to they why mess with heirloom question… @Justin I was going through old coversations this morning trying to decide what to bring over, and [in this thread] I noticed a relevant comment by Lauren Ritz: “Nowhere near absolute, but I did notice that after a few generations of deliberately crossing tomatoes (mostly closed flowers with occluded stamens) I ended up with a population that had majority exerted stamens and more open flowers.” And I still recommend you read at least parts of Darwins’ book, not joking. You will like it. Lots of manual cross pollinations and trials and notes of things.