The pattern marker works surprisingly well and doesn't fade on the foam. That's actually a problem if you cut inside the line. I ended up going back over the visible cut lines with a Sharpie. Tailor's chalk sounds like a good thing to try. The biggest problem with the pattern marker was that it dried out within 20 minutes.

About a decade and some change ago, everyone was into cutting foam, and I was among them. I used serrated knives, electric carving knives, and jigsaw blades. They all worked to varying degrees. I even have a Nichrome cutter, which worked great for through work, though that was not what I was trying to do here. I did run a Bosch T308B jigsaw blade through it, which worked well on single layer foam in the past. In the Kaizen foam, it ended up snagging and tearing the laminated layers too much for my tastes. Another jigsaw blade may work better.

The harsh but consistent truth for me with foam appears to be that my ambitions and expectations consistently exceed my actual abilities.