While this is an excellent plan, and most likely what I will end up voting for, my preference would be to use an Ash Cloud before bolting with an overpowered Skitterleap, leaving Boneripper behind to blast them and stall within the cloud. The only things stopping me from making that plan is the surety that they can sense life and if they didn't dispel the Skitterleap, would immediately give chase.
As powerful as Thanquol is, and though I have confidence he can win this fight, I don't want to chance it. He is a giant glass cannon. He's nearing absurd levels of magic mojo, but we've never invested anything in making him (or other hero Skaven) personally stronger or tougher.
@Xantalos how squishy is Thanquol?