Well, you have a shorter season than I've got but may have more seasonal warmth. My garden is often cursed - cursed,
I say - with a very cloudy, cool spring
! Then, we share those cool nights thru the summer months.
I did live near that lake, the video I posted on your introduction thread, LA47. While there, after a few years I grew only Sub Arctic tomatoes. There are more than 1 sub-variety but I think all are heirlooms from the 1940's. They are very early!
Another open-pollinate, very early tomato is Bloody Butcher that I grow most years. However, since you are putting them out in a greenhouse thru the growing season -- do you really have to go with these very early varieties, LA47?
Burgess Buttercup is the winter squash variety that consistently matures squash that stay around as winter keepers. It is rated about as late as most any other in days-to-maturity and it will have some fruits that need to be used in the first few weeks after harvest, but it has come thru for me for several decades.
This isn't a recommendation but just a suggestion and something I can't seem to get around to doing. There are just a few common types of onions that are grown to produce sets. Stuttgarter is one of these and I grow some of these onions from sets every year. If I did a little research on the correct time to sow seed for these sets - I bet I wouldn't have to buy them! Baker Creek sells the seed. Walla Walla and Utah are sweet onions that I've grown a good number of years. They are heirlooms but I don't know how to tell you to get them thru the winters so that they can produce seed. Sweet onions don't make good keeping onions.
Muncher cucumbers were new-to-me in 2011. Both that year and this one had very difficult springs for starting off the cucumber plants. Muncher did great each year. They are a Beit Alpha type cucumber so they are a little different from the American slicers. I don't make pickles so I just imagine that they would be good for that. Beit Alpha types are usually hybrids but Muncher is open pollinated.
Nantes carrot types usually do well for me. I don't have the best ground for carrots (glacial till) so it doesn't help to have long-season types that hang around in it month after month. So, a short, quick variety like Scarlet Nantes works well.
The Romaines are probably mostly non-hybrids but give the Batavia (aka Summer Crisp) lettuce varieties a try. I like Nevada. Maybe you can get the idea of what I think makes them kind of special just from the names "Nevada" and "Summer Crisp"
. They hold up just as well as the Romaines during the 1st part of our hot, dry summers.
I also grow Jade green beans. Green beans are probably all open-pollinated. I guess it is real time consuming to hybridize beans so that's not the route the seed companies usually take.
We are each other's harvest; we are each other's business; we are each other's magnitude and bond. ~ Gwendolyn Brooks