I’ve done this many times and even gotten F on some domestic connections. But, it is also sometimes possible to get a AF/KL coded, DL operated long haul flight followed/preceded by a DL coded and operated domestic connection. Even if the underlying AF/KL fare is a basic or ‘light fare,’ the DL domestic connection sometimes (not always) books into a non-basic economy fare class (ie. V) and is therefore eligible for C+ and F at normal windows. Just gotta be patient and play around the ITA matrix website and book through an OTA.