Let's talk skilsaw/ portable circular saw issues

I would never check my measurements using the back side of the shoe, as shown in the picture you provided. I would not use wood either, lexan or something similar. I just looked at both of my saws a Skill and an older Craftsman, no adjustments for that type of issue.

I would suggest removing the wood shoe and make another check, using the factory metal fence, making sure you use the same area on the blade (the area right behind the tooth) for the front and back measurements. Put your “new shoe extension” to compensate the difference.

Just the front of blade and fence does the cutting the back side is along for the ride, if it binds on the long cuts yes you have problems.

Generally I find if I start getting bad cuts, the blade is the problem, gummy areas, bent, broken dull saw teeth or just the wrong blade for the job….

My first cut of the day, always is to make sure the blade is square with the shoe……