Just caught up on your question from yesterday. I think you can increase to 1.75 units. Ideally you would not be holding a dose for more than 7 days if you aren't seeing nadirs in the 90-149 range when following SLGS. However, you have to have enough data to do those increases safely.
You said your before bed test would be a +3. That would be a perfect test to get, especially if you can do that every night. If you see a big drop from PMPS, then you know it'll be quite an active cycle and you may need to test later that night, or leave lots of food out for him to stay safe. And those night time tests, in addition to a weekly curve, will give us a better idea how he's doing on a particular dose and whether he needs and increase and it is safe to do so.