Staking on Meridian without Evidence

what would I do?

No don't cut corners, but be very clear to tell the client what's involved and how expensive it can get, then they may say it's not worth the costs. 😉

But don't cut corners, doesn't mean you have to survey the entire ranch for a two acre cutout.

As an older surveyor in the area, I would counsel that the investment in the recovery of original data is repaid over the years whenever there is a felt need to refer to local knowledge. It will be an experience that you won't easily repeat in these "cookie cutter" days. Also don't overlook Washington State Department of Natural Resources assistance.