If I were Washington State and Oregon State, here is what I would do......
1. Either through court or an outside settlement with the departing PAC-12 schools, obtain the rights to the PAC-12 funds that are remaining after the current 2023-2024 revenues are distributed to all 12 schools. If that is not possible due to litigation from the 10 departing schools, then obtain as much of that revenue as possible in a settlement.
2. Approach the ACC and offer them the same deal SMU offered them. No revenue from the conference for 8 years (I think it was 8 years?) and live off the revenues received from the dissolution of the PAC-12 conference over the course of those 8 years. If the ACC says no, make the same offer to the Big 12.
3. If neither the ACC or Big 12 accept the offer, merge with the Mountain West under the PAC-12 banner. However, keep all previous PAC-12 assets to themselves. Essentially, the new PAC-12 is carrying over all Mountain West assets under the name PAC-12. Oregon State and Washington State could live off of the PAC-12 funds for a while and then see how conference realignment shakes out going forward. Worst case scenario, the funding from the PAC-12 could help with a gradual shift over to receiving G5 money rather than a cutthroat shift from one year to the next.