Sounds like a good plan. Lettuce can tolerate temperatures down to 28 degrees, so cover them up if it’s going to be colder.
You might want to look into a cold frame. They’re easy enough to put together, and will really extend your season in the spring and in the fall.
It doesn’t have to be this fancy, but here is the general idea:
https://www.growveg.com/guides/how-to-make-a-cold-frame-step-by-step/
And, even though you didn’t ask, my favorite books about growing year-round and/or in cold climates and short growing seasons are by authors Elliot Coleman (Barbara Damrosh is his wife, she’s good too!) or Niki Jabbour.
My petunias and snapdragons are germinating, having sowed the seeds last Sunday in my BioDome. By next weekend I hope the pentas and pansies are also up. Shoveled tons of snow out of the new greenhouse floor today, and from around the outside edge of the framing. Need it to dry out. Snow nearly 2 feet deep in places. Could not just wait for it to melt. Need to get the polycarbonate on ASAP.
Cheers for warm and sunny days!