I taught largely in Malaysia and happily dived in only a rash vest and boardies. Being cold wasn't such a big deal as as soon as you get out of the water it's lovely and warm.
If you are worried about work permits try the Perhentian Islands in Malaysia. Season runs Feb to October, although there is very few people there when the season conflicts with Thailand's. So April to September is better for earning. No-one checks work permits regularly and we always had advance warning of immigration raids as it was 30minutes from the dock to the islands, plenty of time for a phone call. Standard Visa is 3 months, so less renewal costs for visa runs when compared to the monthly run you would have to do when trying the same in Thailand.
I will add I had a work Visa my 2nd time in Malaysia.
If you are worried about work permits try the Perhentian Islands in Malaysia. Season runs Feb to October, although there is very few people there when the season conflicts with Thailand's. So April to September is better for earning. No-one checks work permits regularly and we always had advance warning of immigration raids as it was 30minutes from the dock to the islands, plenty of time for a phone call. Standard Visa is 3 months, so less renewal costs for visa runs when compared to the monthly run you would have to do when trying the same in Thailand.
I will add I had a work Visa my 2nd time in Malaysia.