@John ********
and I think you have most of the suggestions that are viable. Your reticence to contact the consulate is your biggest stumbling block to you finding out IF you can get a 6 month METV or not.
Believe me you're far from the first foreigner who wanted an METV but was either self-employed or un-employed.
Your choices are
continue on SETV's until you get a red stamp and can't get them anymore
go down the ED visa route
go back to your country and get a 6 month METV
OR
you go to the closest thai consulate on this side of the world (Perth Australia) and get a 6 month METV from them.
CONTACT the consulates :)
Good Luck (y)