I don't think it is "reasonable" to "expect" to do something which you have decided not to do. I also do not think Chase cares about the distinction between "basis" and "gain", only about cash flow.
What if I'm not sure how much to withdraw?
I've actually asked this a number times by secure message. Answers have been wildly inconsistent.
I agree with you that cash flow is the better answer. I would think what they really care about (or should care about) is capacity to repay.