Thanks, this helps. I should have been clearer in my original post - when I said "withdrawals," I meant withdrawals from the Roth, not withdrawals from the tIRA to fund the Roth. But I think you all got that.
So Close makes a reasonable point: as long as I have all of the documentation, I'm safe; that is, even if I accidentally neglect to submit something I'm supposed to, at least I'll have all the evidence in case of an audit. That makes me feel a little more relaxed.