Google Maps is quite helpful as you can see hotels close to train services. MRT/Skytrain are efficient and cheap so no problem staying further out but try and avoid peak commuter times.
Best piece of advice👍It’s a big gamble thinking she’ll be happy settling into a completely different environment and culture without her friends. Sometimes it works, sometimes it doesn’t.
Safest bet would be to use a border run service. They’ll take you to the border and make sure you get back in. You should be okay to fly out and back in, just make sure you have the three proofs…onward travel, accommodation and 20k baht or equivalent in cash. Immigration are asking more questions of people doing back to back visa exempt entries. Things work a bit different in Thailand than Europe! METV is another option.
Just wait until closer to the time. Nobody knows what the rules will be next week far less December. Could still be 60+30, it could revert back to 30+30, or you do 30+30+border run or tourist visa. Who knows, you’ll get your time one way or another 🙂