we are talking Thailand who cares about the states. I simply quoted what happens in my home country and they will chase you through court and get paid.
your 1 month behind in payment, your giving notice, so what do they get from you breaching the contract by 4 months ? Just 1 months deposit ? Back home you be liable for the whole 4 months or until the unit was re-leased.
You can fly in and out as no official restrictions but eventually Immigration officer will say no as they don't like people milking the system to live in Thailand. They want to see a real visa