You do not require a masters for a GS-12. Many entry-level engineering positions (hard or soft) have a target grade of GS-12, so if you do your job at all you'll be there in a few years. If you're even slightly serious you'd likely snag a GS-13 position within 5-10 years. If you're in a low-COL area, ~110k is reasonably competitive. Also keep in mind that you're working 40-hour weeks -- none of this exploitative 60+-hour week death march nonsense.
