ok... Well since there is no Thai Embassy in her home country that is not an option.
I'm not sure what road blocks she might run into as you write... other than that it could take longer time and that they would do background checks etc...
Are you saying they wont even accept her application?
I know (most have changed already). However that doesn't change anything of what I wrote. She could still go to one of these countries to apply... (online, not by a visit to an embassy).
You don't apply online before you leave Thailand. You do it IN the country from where you are applying. In the application you need to show the address to where you are staying AND your passport page with an entry stamp to the country.
I guess her only choice is to travel to a country where they accept applications from people who are visitors in the country (like most countries in south east asia for instance). Unfortunately I don't have knowledge if any European embassies does. She could ask embassies in neighboring countries to Ghana.