I think tonight you reduce again down to 1.25u. If you are worried and Clarence isn't terribly high, then back off to 1u for tonight and resume with 1.25u tomorrow. Clarence is obviously getting extremely, almost too, good drops out of the 1.5u especially given he looked to be in a bounce this morning.
I think you did exactly what you needed to do and you kept him safe and that is what counts. Until you go through this a couple of times and figure out what works for your cat, it's hard to say do X,Y or Z exactly. You do what you need to do to get numbers up when they are that low and try not to shoot BG to the moon but if you do it's no big deal. I'd say you hit the nail on the head.
As for foreseeing what he might do, you gave a lower dose than yesterday and BG at +3 was a tad higher than yesterday so you had no way of expecting/predicting that 50 reading. The important thing is that you handled it like a pro and didn't shoot him to the moon. Remember, when he goes into low numbers, his defences kick in too so while 176 may seem high to you, believe me, I've seen kitties go up a lot more than that. Safety first. BG will come back down if you boost a bit too much. Far better safe than too low.