I was in the same situation recently, so I flew to Phnom Penh for a 3 day weekend. Got my new visa exempt stamp, and a nice little trip to Cambodia. No Problem.
I'm 62, and walk with a limp, which is at it's worst after 20+ hours of flying and layovers. Many times I'm directed to the fast lane. Now I ask, and they usually say yes.
If you are on a Tourist visa, a trip out of Thailand is required within the length of your Visa. I'm assuming 60 days + 30 day extension. So a ticket required within 60 days. You can book a cheap flight to Cambodia or Vietnam for around $50. There are other options . As often mentioned, Thai officers rarely ask for exit ticket. I've been asked maybe once, in many trips. However, airline gate personnel have asked me for an exit ticket on a few occasions. I recall one airline person actually counting the days on her fingers.
To be safe book your flight out of Thailand to Vietnam or Cambodia before your 60 day visa runs out. Maybe you will find a changeable flight. The low cost airlines, probably not, but their fares are very reasonable. Like 50 USD one way. Many will say they are never asked about this flight out of Thailand. I've been asked to provide proof of a flight out a couple of times, usually by airline personnel.