Most Immigration Offices let you apply between 45 days before and the last day. I would say go now and get a re-entry permit once the new Extension is stamped in your passport.
If you come back on the 15th, 1 day hotel, you have a little time left to organize all.
Not if you talk about the 90 days report that you make if you are 90 days inside Thailand and the three month needed to keep your deposit into the Thai Bank. Total different things as you noticed.
The banked money of 800.000 thb must be in the bank 2 months prior application until at least 3 months after.
The rest of the year it can not be less than 400.000 thb, you may have to show this when you apply again as you promissed to follow the rules.
If you like to use next time the monthly income it must be at least 12 months prior application date a minimum of 65.000 Thb a month as foreign deposit into your Thai bank account.
For a month or two and a few days to drop your bags, I would advice the Single Entry Tourist Visa which will give you 60 days on entry and can be extended once with another 30 days based on tourisme. apply:
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Vaccinations, quarantine etc is part of the Thailand pass, choice your plan here
Covid is no reason for overstay, people are staying over 2 years inside Thailand using the special Extension of Stay based on unable to travel. IF people follow the rules to inform a medical service after being tested positive, they will get help.