Given we completed phase 4 of Border Offensives which gave us 3 RZ mitigation and we started the last turn with 28 RZ mitigation needed, we should be at 25 RZ mitigation needed.
The Plan required projects are:
Border Offensives 5 (3 RZ mitigation)
Coordinated Abatement 1-3 (6 RZ mitigation)
We are likely to do the deep glacier mines and the containment lines
Containment lines 1-3 (9 RZ mitigation)
Deep Glaciers 4-5 (4 RZ mitigation)
For a total of 22 RZ mitigation, meaning we need 3 more RZ mitigation
So yes we either need a RZ MARV or 3 RZ tib harvesting. The latter will cost on the order of an extra die, but will produce 3 times as much rpt. That's why I said the MARVs are not strictly required.
YZ->GZ conversion by way of securing YZs being carved out by RZ abatement efforts may result in more RZ Border Offensives and Deep Glaciers. It'd be more expensive in dice, however.