Thanks everyone for the suggestions. This is LAS mid-week, mid-day, so mostly leisure travelers and usually there's plenty of UDU's to go around for elites. However, my flight does seem fairly full this time around.

I'll assess the situation at the gate for trading directly with another soldier on the battlefield; unfortunately one drawback is that I'm sure the gate agent won't let me bring the carseat onboard for that scenario. I've done OLCI for F so at worst can't complain about the extra space and it's a short flight anyway. (I picked the last row of F to minimize disturbing others.)