Seems like you are right on the borderline for standing 6 out of 8 hrs. There are no guarantees especially with back surgery. It could make things worse. I myself,would pass on surgery. Medications do little to relieve my pain plus I have a heart condition and taking anti-inflamatories is sorta a no-no. Get a second opinion. Do a google search on SSDI-lower back pain. Check out the SSA blue book for SSDI.