Shameless Plug: Kytephone (https://www.kytephone.com/) adds a de-facto multi-account support to any Android phone or tablet running 2.2 or above.
It's aimed at adding accounts for kids and while it's not as extensive as the baked-in one (kids can't have their own gmail account for example) it does come with goodies such as time limits for games.
If you do want to obey the rules there's probably nothing in the rules about not using an account created by a parent, indeed acting as agent for that same parent when creating the account is probably within the rules too.
It's aimed at adding accounts for kids and while it's not as extensive as the baked-in one (kids can't have their own gmail account for example) it does come with goodies such as time limits for games.