OK....remember 2 inches on each side for 4 inch total....and what you will find out is it widens even farther than that...at least you realize that it does widen...that's half the battle
PS...if you run shocks with huge PSI or spring overs tight on travel you will notice that the squat or widen only happens rarely...but when soft it widens just from sitting on sled...and the fatter you are the more it widens
I completely understand how suspension geometry works.
Also remember that is you ride with your preload set so that your a-arms are horizontial with you on it, your ski stance will be at its widest point. Therefore any suspension travel, UP OR DOWN, will result in a narrower ski stance then what you started with.
So it goes both ways, you can make it always narrow up.
Again, I will say it is not as dramatic as an old trailing arm sled. Those would widen or narrow alot.
Also affecting it is the length of the suspension travel. The more travel, the more the stance will change.
Suspension travel also affects bump-steer. I will check how much the bump steer changes during the full travel as well. Though I think this really means nothing on a mtn sled. And only means slightly more on a trail sled. The only type of riding I would even think about correcting it would be oval racing and MAYBE snocross racing.
Same with adjusting Ackerman into the steering.