Invite an accountant to the Client Portal with invoice-only view access

I want to be able to invite my client's accountant to the Client Portal, but restrict what they can see to invoices only — not proposals, daily logs, files, schedules, or anything else.

Right now there's no way to set per-invitee permissions in the portal. Everyone who gets invited sees the same things. I need a way to give someone view-only access limited to a specific section (invoices in this case).

"Would also invite their accountant to the clients portal but only wants that accountant to view invoices not everything else, so view/limit permission access for invitees to portals."