Jenn...you test enough to do the Tight Regulation protocol if you want to (not sure which protocol you're using) and there's also no real need to do a "curve"....if you just get tests in at different times throughout the cycle, that'll tell us more than 1 cycle of a "curve" will.
If you think of the spreadsheet like a puzzle, if you have pieces of the puzzle sprinkled throughout, you can see a clearer picture. Look for places on your spreadsheet with lots of white and try to get some of those places "filled in"
In TR, we don't hold the dose as long since it can lead to glucose toxicity ....I think I'd consider taking him back up to 1U, but you might try feeding him something higher carb, especially at night when he tends to do those fast drops.
Some cats actually do better with at least some carbs in their diet! It might be worth a try with Sampson!!