Friend lives in San Francisco Bay Area, about 9b. She had a Meyer Improved Lemon in a pot she would move in for the coldest part of her winter, about 6-8 weeks. Nights it might frost she would wrap it up if it was outside.
If you build a bit of a winter cloche of
wood and cover with sheet plastic, and perhaps put a string of NON-LED Christmas
lights inside (on the wood frame) to plug in on coldest nights plus an additional cover for night, you should be able to keep a Meyer. The cloche would have to be big
enough to give the tree space (leaves can't touch the covering) but not much extra.
An established in the ground Meyer lemon in the space you describe, might make it. Keep it pruned to keep it smaller, hence easier to deal with, and it might happen. Good Luck.