AirAsia have the below flight starting next year:

Bangkok-Phnom Penh: 6:55-8:00 am

Phnom Penh-Bangkok: 8:45-9:55 am

So same plane back and forth, but there is probably no time to pass immigration in Phnom Penh.

Is it possible to use this flight as a visa run and be home for late morning coffee?

1. Will AirAsia allow you to "transit" in Phnom Penh?

2. When doing a land based visa run to Cambodia, the Thai immigration insist you do enter and exit Cambodia. Same requirement when flying?

With airtravel stamps of entering and leaving another country are not checked.

If no luggage and airasia allowes checkin in through internet i suppose you could just transit. But ask the airline.

You must be stamped through immigration in Cambodia the same as doing a border run.

For sure it is not enough time to do it.

Get the later plane back - at least you can now come back the same day.

I think you should be okay. If you don't have any checked in baggage. I was just there and it took 5 minutes to go through customs. If you do a web check in you should be good to go!

What you don't want to do is have to line up for a Cambodian visa on arrival. Might take as long as 20 minutes. Then it's unlikely you will make it. You need to get a visa beforehand.

Also there's no Air Asia automated check-in at PP airport. But the counter agents are very fast and plenty. The airport is very relaxed and small. If you want to try the quick turnaround, you leave immigration and customs areas and go through the exit.

The short exit channel is quite open on both sides. You will pass several mobile phone kiosks. Then you will see many waiting people and taxi drivers. No hassles there. Where they wait, turn left. (Turning right gives you the washrooms.) Go straight 10-15 metres. When you see the parking lot and waiting taxi and tuk-tuk touts, turn left immediately before you reach them. You're still inside the airport building proper. Follow the open corridor, passing fastfood places, you jog right slightly and are now walking along the outter terminal floor to departures. Keep going straight, through the wide entry doors where officials do occasional checks. To your left, inside is the Air Asia departure desks. Simple. Takes maybe 3 minutes from exit channel to entering departure ticketing (ground) floor.

I think the best idea is to wait for the mid-afternoon flight. Take a trip downtown $5-$6 by tuk-tuk OUTSIDE the airport perimeter fencing. Tell them Sorya (so-REE-ya) market. Wander around the mall and nearby New (Central) Market, get something to eat, have a coffee. Take tuk-tuk back to the airport $6-$7. Yes, can be bit more outbound.