I have to admit, I didn't get how you was going to incorporate the platform that you built into your build, but now you have started building the chip pan it really ties everything together, and now I can fully see your thoughts about the mill stand not being wide enough.
I actually had ideas to fill the mill stand with epoxy granite or just regular concrete when I get my mill, but after seeing your build it may be best to build a platform like you did then sit the mill on top of it, perhaps even still filling the base for extra weight.
Looking forward to more updates on your build.