Just wanted to update the 30 day extension worked as was mentioned in the thread, here's details in case it's helpful
1) Made an appointment on line for 10am, a week before 45 day expiry date
2) Downloaded and filled TM7 at home previous day with photo
3) Also made copies of main PP page, tourist stamp page showing date valid to, and copy of webpage showing confirmation of appointment date/time.
4) Went to the IT Square office 30 minutes before appointment, at the desk they checked document and gave two forms to fill, name and signature, and told to go sit outside the Immigration Officials room
5) Few minutes before 10AM staff person came out and called out " Online appointments", went up to her she checked online appointment document and lets me in the room
6) Waited a couple of minutes for IO and then went up to her, she checked doc, took picture and paid her the 1900 Baht fee, was given a token number, was told to go back to outside seating area and wait.
7) 5-10 minutes later IO comes out with some passports called out token numbers, handed her my token and collected the passport with 30-day extension stamp
Was heading back home by 10:30 am, quite efficient I would say.