Your company would have to partner ina a Thai Registered Company, and as your employer they would have staff or an Agent begin the documentation to get you a Work Permit Application started and then you would apply for a B Visa
I believe you can get another METV and do it again. You description of your travels will show as stamps and stickers in regional countries - you didn't spend a full 7 months in Thailand. The METV in my opinion was designed for just that.
Jimmy, Robert has spelled it out precisely what you have to do to get a One Year Extension of Stay.
But please note the Non Imm O Visa you get in Sanannakhet is for 12 months - However it only comes in 90 day increments (permission to stay)... At each 89-90 day mark you have to Exit Thailand and Reenter - do a Border Bounce. Upon Reentry you will be stamped back into Thailand for another 90 days. This is a routine event - nothing to it except the time, travel and expense of going to a neighbor country's border. And also take note - you can perform this out and back in - from 15 minutes to 30 minutes to 60 minutes - then you are back in Thailand. You do not go to the Thai Consulate in that neighbor country.
If you have booking documents for a flight out of Thailand scheduled within the proposed 30 day Extension, I don't think it will be denied. You would be scheduled to leave Thailand - so why give you a hard time over 30 days?
In the uncommon event they should deny you an Extension, I think they would do nothing but let your Visa stay run out. But if you go now - then you will know absolutely and have time to plan
I do know of two people who got an Extension on a Visa denied at Immigration. They were instead given a denial and 7 days to leave. But this is not wide spread.