Can I apply for a Non-O visa in Thailand without leaving the country?

You can apply while in Thailand but you will have to leave the country and use the non o to. Re-enter to get the right stamp. That could be a few hours border hop. Once you are 60 days on the new visa you can do extension

Yes you apply here

You can apply for a non-O visa in Thailand without leaving. It doesn't matter if it's tourist visa or visa exempt. It will not be a "single entry" visa as you will already be in Thailand, so it will be zero-entry. You just need to make sure you have enough time as you'll have to have at least 14-21 days remaining on your permission to stay at the time you apply. If you don't have enough time they will reject your application as they need time for a consideration period. As a female married to a Thai male you will not have to meet any financial requirements, just the paperwork requirements.