Sorry about this, not usually on during the day.
If you can monitor and have hypo kit I'd try to shoot full thing and see what happens, but test for sure at +2 to catch the beginning of possible drop.
otherwise, I would think 2U is good, but again with monitoring
If you can't be around, 1U?
It's a little hard to pin the tail on doses because his body is doing something, so we just want to start figuring out what we can shoot when OR get to something you can shoot consistently