I think there is too much exp in Act 1. In particular, we spend very little time at level 2, which is not great because this is the same time we're introduced to controlling a party of 4 characters of different classes. Early levels in tabletop are often sped past because they are boring and highly lethal, two things that aren't as relevant in BG3. The former because you're controlling a party of 4 - with 1 extra NPC companion to switch in if you get bored - and the latter because of Scrolls of Revivify and/or reloading. (I suppose the former isn't as true for multiplayer, but eh whatever)
I'll slightly downgrade your suggestions: Act 1 should cover levels 1-5, Act 2 levels 5-9, Act 3 levels 9-12/13. (I'm assuming Act 2 will be longer than the other acts).
I don't want level caps. Doing all of the content should result in you being a slightly higher level (6 and 10 respectively for Acts 1 and 2) than "expected", and avoiding most of the sidequests should result you being a slightly lower level (4 and 8).
