I've been working on this all evening, and being somewhat new to Meshcam there is lots to learn. I changed the tool settings to make sure it only does one pass, which while longer than the actual mill cutting length is fine because it's 6lb foam and there has never been a need for mulitpasses in the past. This has reduced the memory usage to about 6gb of RAM, so it must have made a pretty significant difference. Also, I upped the tolerance a bit from the .025mm to .04mm, which probably also helped. Still waiting for the toolpath to finish (been a while, but it's going to be big), but I'm pretty sure it will finish up this time.
I do have to give kudos to Meshcam for the efficient use of processor cores. All eight cores were pegged at 100% for all but the last stage of linking the toolpaths, or for around 20minutes straight. Not sure how much my computer liked that, but I can only think of a handful of multicore hyperthreading applications that can even do short bursts on my computer at 100%, let alone 20 minutes straight. It's a lot more satisfying than watching most applications (even 64bit) chugging along on one core with 88% of the computer resources untapped and I'm sure quite a lot faster as well. Very impressive, IMHO.
I do think that eventually the memory issue will come up again for me as this was only a medium sized topo and the surface area could easily double for others. I would guess that if I double my current RAM, there probably won't be an issue, but it might be nice to be able use page files on computers that don't have quite as much resources, like my laptop. So while I've worked around it for this test cut, it would be nice to know if there is a solution for future reference.
Thanks!
-Mike