I used a bit of subterfuge. Walked into Krungsri (yellow bank) a few years ago znd using Google translate asked if there was a bank near here where I could deposit 10 million baht. Yes they said and fell over themselves to help even opening a Krungsri Prime VIP prime account for me.
When they eventually asked if I was going to deposit the whole 10 million today I said no. I will deposit 100,000 Nd transfer the rest next week.
I still have my vip account with all the perks and never deposited the lump sum!!
If they are booking you and your baggage through they should check everything. If its a short hop where you reclaim your baggage etc then checkin again then they don't need to.
if their is a penalty there must be a cause. The op said her doctors couldn't do it so it can't have a sanction if a possibility of breach doesn't arise.
Go on the registration website for doctors in your country. Choose one in your area and enter their registration number and name and scribble a signature. Job done.
I was told it is possible but you need C of E $100k insurance and 10 day pre booked and paid quarantine. Was suggested I took the 900 baht flight from Wattay to Udon or DMK.
I don't think anybody is sure right now. The Covid visa was for people who couldn't return really not so they could just stay in Thailand so it may be that is its possible to return to your country you will have to do so then travel again with the correct visa. As I say its unsure at the moment. Maybe clearer in January