When I flew them it was open seating and you just sat wherever you wanted but there was only 4 pax on-board. They will ask for your weight at check-in so they might assign seats based on weight & balance but otherwise you should be able to sit wherever you want. If you get there early, you could try asking for the first row. I'd recommend the middle seat so you can sit right behind the pilots with a great view of everything that goes on.