We used to use plastic or canvas and “build” a shield around citrus and other fruit trees. Use rebar or something to drive into the ground and then attach a 2X2 or PVC pipe and make a frame for the shield.
If the temps will be in the low 20 range, and additional blanket (or a light bulb on the inside of the enclosure if it is close to an outlet) helps to keep them from freezing. All you need to do is raise the temps to 32 or more.
Thanks for the tip - I have the material for that and will get cracking. If your screen name indicates your birth year, it’s the same as mine.