> Was I missing something? Is there a way to let Forth keep track of where on the stack "foo" lives if it is needed several times in a subroutine instead of always shuffling the stack or counting the elements on it?

I'm not a Forth novice, much less an expert, but my impression is that the answer is that if you spend much time thinking about the location of variables, then you're "doing it wrong"—to steal the phrase, trying to write C in Forth, rather than to write Forth. My understanding is that the emphasis is on building highly domain-specific languages out of many small words, each of which is re-factored so much that it never needs to keep much track of any, or much, shuffling of variables on the stack.