That doesn't really make sense, PVV can only get into a coalition with the VVD, all other options are ideologically not possible. Making either big just heightens the chance of a PVV coalition. Yeah if VVD becomes the biggest they might choose another direction than PVV, but you'd have to rely on people like Halbe Zijlstra to keep their promise pinky swear. And actually only Rutte ever said that he wouldn't be in a coalition with Wilders, so if he steps down it's free game for the VVD.
I think the only strategic vote would be to vote neither. Or better, D66, they're similar to VVD and would never get into a coalition with PVV.