They have ways and means! Starts with the ex-wife and her sisters! 🤣. A visa/extension in breach is still the same as being on overstay @500 baht/day with possible deportation/ban
No checks made on home country bank account. A bit confused, why would you want to cancel a health insurance policy? You are aware it's quite easy to have an illness or mishap in Thailand? I use my credit card insurance which is ongoing.
The other difference is with the OA you do not have to transfer any money into a Thai bank account, you use funds in your home country bank as proof of finance. You can also get two years stay from an OA without having to apply for any extension simply by doing a border bounce before the original visa expires