@Scot ******
or make sure you have your TM30 filed in pattaya, get your bank letters, documents, copies, etc and go try to apply for the yearly extension. Do it a month before your current stamp expires so if they say you can't do it there you have time to come back to bangkok and get a hotel have them file a TM30 showing you do stay in bangkok and can file up here for the year. Once you get the year you're pretty much free to travel to your hearts content.
Please realize no disrespect was intended or implied BUT many MANY people have done exactly what you intend to do and get a lot of push back or get denied outright.
Even a thai visa/extension guru like myself 😉 wouldn't wager what the real answer will be from the Jomtien Immigration office when you show up with a Chaengwattana Non-O stamp
Good luck, hope it works out, Slog on over and as they yourself so you really know.