I don't think so, because even if it is open AA will still need to make a hidden dummy booking. I haven't tried, however, so I guess it is worth a try. Note that even trying to book a seasonal flight becomes a problem (it can be solved, but it is a hassle) when the schedule is not loaded at the time of booking; to book an ANC flight out of season I had to go through loops, and the supervisor made all kind of "if anything happens you are on your own" type of notes on the PNR.