When I said cold climate, I wasn't kidding! Haha! I've moved even further north than I'm used to, no one even produce grains here... The thaw goes in late May, but the summers are (usually) quite warm, and many hours of light. Almost midnight sun. So anything growing fast in regular temps should manage. I have some brassicas now, they seem to be doing fine. Potatoes should be a safe bet too, though I'm not sure how good they are for chickens. Lots of starch and little else.
Haven't thought of hoop houses and grow tunnels, that's a good, inexpensive idea! I got lots of fiberweb crop fleece and see through plastic already. Will stop the squash from drowning in the rain too, I assume.