Darn! He isn't making this easy. Of course, the best thing would be if you were home to catch him on the rise and give him a small amount of insulin. But I do understand that your life is complicated. I would test as you walk in the door and if he is over 150, give him a shot. (You may have to throw the schedule out the window now since he is giving you low numbers at preshot times anyway.)
His numbers are very encouraging. Is there any way to change your work schedule so it is a little more flexible? Or take a few sick days? If you can take advantage of these lower numbers and catch him on the rise, it is your best change for remission. And I know that is your goal before you have to leave for Europe.
Did you see that Gayle and Shadow responded to your post on Health and live in Toronto? Maybe she, or some other member she knows in the area, will help you find a FD cat sitter.