If you go to vietnam, keep in mind you have to get an appointment online for the embassy , in Hcmc and in Hanoi, and the slots are booked long in advance.
After 16 april, every officer can catch her. If you fly domestic the officers at the passport check , may or may not see the expired stamp and can catch her.
Safe way , you dont fly to Krabi, you fly to Phnom Penh or maybe Laos , stay there 1-2 days and then fly back to Bkk to catch the flight home