The short answer is yes! I frequently book spur-of-the-moment well within the 105/90/70 day window for booking online. I've never had a problem getting a PALO ressie once I've boarded. The selection of dates/times may not be exactly what you'd like, but you shouldn't have a problem getting a reservation if you go right away, as soon as you get aboard. Just ask one of the CMs that welcome you aboard as to where to go and what time the PALO reservation folks will be there.
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