Yep sorry, mighta got previous wrong, 90 days would start on entry to country, you'd probly need to come in twice (with a re-entry permit in between) if you have a 60 day limit. Some Offices allow extension applications 45 days before expiry (eg Chiang Mai), not sure re Chonburi
Thanks. Maybe good option, but not sure if 21 days required in Cambodia to be eligible for 1 night only quarantine upon Thai return? Maybe if only in Thai and Cambodia for last 21 days, can be eligible? Otherwise, Sandbox Return maybe best option? See what happens.