@David **********
since Phnom Penh is a shithole, I recommend a flight to Siem Reap. Visit Angkor Wat. If it's about a border bounce for another 60 day stamp, you can go by van to Ban Pakkad. Start is 6.00am, back in Pattaya about 3.00pm.
Book a flight from BKk, not from DMK!