Jonah Savaiinaea is my PFN mock draft go to if the top three OG are gone. You usually have to take him c.40 though and the guards get really thin / picked clean after pick 60.
I think I've reached peak mock draft (R1-4) result now with this. I'm usually an 'Edge/CB in round 1' drafter, but Seattle really, really wanted to move up for an OT and the chips fell just right for an offense-heavy draft.