I will be spending the night near CDG for departure the following morning. I am hoping to get a test nearby that same evening. Any ideas?
Yes, almost any pharmacy, and a host of supplemental on-the-street testing stations, can administer an Antigen test. If you are traveling to the US, the results are instantaneous and valid for 3 days.
I would not wait to do it at the airport.
Since you are staying next to the airport, here is the info for the testing site inside the airport: https://www.parisaeroport.fr/en/passengers/services/covid-19-test-pcr-antigenic
I agree about not getting tested just before check-in in case you've inhaled some shedded virus, which will cause you to test positive. Or be extremely vigilant about masking for a few days before testing.