How to respond to this question: present perfect simple or continuous?

This is from a grammar book about aspect:

"What have you been doing today?" or "What have you done today?"

The best reply in both cases is in the same form as the question, but a present perfect simple reply to a present perfect continuous question shows that the job has been finished when it would not otherwise be clear. For example: "What have you been doing today?" "I have painted the bedroom windows." (clearly it is not in the same form)

My question is, if the best reply is in the same form, can I respond by saying "I have been painting the bedroom windows" when the job has been completed ? I have spent my day painting the windows, the job is done now, but I want to emphasize the activity, I want to communicate what I have been doing, not the fact that the job is finished.