The vp actually has nothing to do...so he could advise the AG via Trump
Advise is one thing. But I think you would have separation of powers issues if a sitting vice president had to be approved by the Senate to be AG. And I would hope that whoever Trump picked as Attorney General would be capable of doing the job on their own and wouldn't need advice from the Vice President.
On top of being VP he’s also president of the senate. I would love to see Cruz as the Boss of Mitch McConnell, or Dingy Harry.