Ok, it looks like I'm good.
The "Maximum Pell Grant" eligibility apparently uses AGI, and AGI only.
The section of the handbook you referenced applies to the "Calculated Pell Grant", which considers some untaxed income, such as IRA contributions.
We intend to qualify for the former, so we shouldn't have to worry about this "untaxed income". That's my reading of it, anyhow.
Thanks!