So here is what I am thinking for my remaing plantings:
Beets: Boro beets take 50 days so they might still be possible to grow. (presoak seed water and fish fertilizer then plant planting.) They might even do better than spring plantings, start in heat, finish in cool. The limiting factor is the declining daily sunlight. If no beets, then beet greens! Boro is a good beet variety. (Will plant tomorrow!)
(https://www.johnnyseeds.com/vegetables/beets/round-beets/boro-f1-beet-seed-3300.html)
Lettuce. Started in jiffy pots, need to pull up last determinate tomatoes to plant! (You could presoak some early ones like red oak leaf and try.
If started tonight, Bossa nova zucchini is 45 days. (Hopefully) Probably only a few zukes and you would need to hand pollinate! I recently put in tomatoes, Burpee long store transplants. Total crap shoot and I knew it. Still who knows! (Graft the suckers to another older tomato?? might work. As you point out, addition of some frost protective garden fabric would help extend the season, especially for kohl crops which handle cold well anyway.
Also turnips and spinach!
There's no telling here. We've had some Winters where we never got a hard freeze until January.
Meanwhile, May had June's weather, June had July's and Aug is looking to have Sept's weather.
That could mean Sept will have Oct's weather. Or not.
Whatever I plant for Fall will have to be in nice straight rows to make it easier to cover them. I've got some 11 gauge 200k psi high tensile fence wire that's very stiff. I can make 3-4 foot hoops out of those and get some cheap plastic for row covers. Old sheets or cut up tarps would work too for overnight. Even when we get frosts in Oct/Nov the long spells of cold don't set in until Dec/Jan/Feb.
Going to start some seeds today, probably just greens and lettuce and then it's on to firewood which I'm once again behind on. My wood stove likes very well seasoned wood so I should always have all I need for Winter by the preceding Spring so it has all summer to dry. I'm going to cut trees up near the house where I have a ton of small ones. That and drive the rest of the property and likely find a couple of good sized standing dead trees.
Yes, that fall planting calculator is nifty for sure.
Keep in mind that pretty much everything on the list is, at the least, slightly tolerant to frost, and will be fine outdoors until the first hard freeze.
I’ve had kale and collards last until spring through some very brutal winters without any covering.
I planted an 83 day sweet corn on 8/12. I think my chances for getting a crop from that are pretty good. August-planted corn has succeeded for my every time I’ve tried it.