Can't help you with the requirements for the 40k per month option as I am using Money in the Bank.
But this was the list of documents we submitted last January and all were accepted and I got a new extension after the "under consideration" period
1) TM 7 Immigration Form
a. Photo Size 4x6 (2 x) to stick on TM 7
2) Copy Passport
a. Copy Face Page
b. Copy last Non - O visa
c. Copy Last Entry Stamp into Thailand
d. Copy Last Extension of Stay
e. Copy TM 6 Departure Card
f. Copy last 90 day report
3) Copy Yellow House Book Husband + Original
4) Copy Marriage Certificate (Khor Ror 3) + Original
5) NEW Marriage Certification (Khor Ror 2) obtainable from Amphur (Max. 1 day old)
6) Copy ID Card Wife + Original
7) Copy House Book Wife + Original
Family Photos
a. Couple sitting on Bed
b. Couple outside with House Number clearly visible
c. Couple sitting in Living Room
d. Couple sitting outside House (near front door)
9) Map to the House (Complete with GPS Coordinates)
10) Bank Book Fixed Deposit from Bank on day of visit to Immigration
a. Transfer min. 1000 THB to Fixed Deposit account on day of Extension
b. Update Bank Book @Bank Branch
c. Bank letter Fixed Deposit obtainable from Bank
d. Copy First Page (Name)
e. Copy relevant Pages
Everything Double Copy (and pictures must be in color)