I'm writing not because I'm an expert, but because I find the question interesting. Seems to me that increased wheelbase would be more beneficial from a standpoint of resisting the car's ability to fling the front end about, (both side-to-side and upward, with the rear tires' traction being essentially equal) rather than helping in a situation where the rear tires are lit up to whatever extent and the car's going sideways. The further out the weight of the front end is, the harder it is to swing it out of whack, the more likely the front tires are to stay aimed downtrack and not at the wall, and on or near the ground and not aimed at the moon. I think the degreed engineers call this "polar moment of inertia" or something like that.
So I think that if you wanted to simulate 20" increased wheelbase, you could essentially do it by moving or adding some amount of weight to the front.
As far as front track width, I've looked at the narrow tracks on some cars and thought that they might as well have been tricycles, but like DRE said about wheelbase being irrelevant as long as the car's going straight, I guess the same applies. If you're in a situation where you depend on an outrigger effect, you should have been out of it sooner...