Hmm, so, in theory (and maybe in practice), instead of writing a new stack-based virtual machine, one could use Forth instead, and write a compiler (for a given language) that targets it. I wonder if this has actually been done?
VMs usually have a fixed set of instructions, because the compiler needs to know how to cleanly map the language semantics to them. It's just that most stack machine bytecode tends to overlap with a subset of Forth.
