It's very easy to stay 11 months without worries if you time it right. Come around June 5th with a 60 day tourist visa, extend it for 30 days, then do two land border runs with extensions for an extra 4 months. That should then take you right to the beginning of January when you can then do 2 more land border runs with extensions. Voila!
Of the 10's if not 100's of thousands of people who have taught online in Thailand, I have not heard of one getting busted. You fear mongers are hilarious.
My first thought was.....Step 1. Get new passport and continue with process . Step 2. Sell old passport on the black market. Step 3. Profit. But then I realized we are 2 weeks past when you lost your passport and you still have basically done nothing. So.......chok dee kap.
They don't care if you are sick. They care if you go make someone else sick. I don't think there should be quarantines but that is the logic you might be missing.