Finally found the cause of my power problems, but not without breaking a few more eggs. The voltage fluctuation from inductance was negligible. So I fired up my control panel and everything seemed to work fine for about 30 seconds, then the spa panel kicked out. I assumed it was GFCI related, Figured I would reset and try again. About 20-30 seconds in it kicked out again. Went outside to look at the spa panel and as soon as I lifted the cover I smelled burning electrical smell and noticed smoke coming from my GFCI breaker. Obviously the fault was not GFCI related, so I started measuring power at the spa panel.
Now I was getting 176v on one leg and 68V on the second leg. After a WTF moment I started tracing everything back to the source. Inside the original welder plug that I had always assumed was ok and never opened and inspected because the voltage was a perfect 123v on both legs I found a broken ground connector that was making intermittent contact.
When I took the heavy ass extension cord out the socket flexed back enough to make a good enough connection to measure correctly. With that 4 gauge extension cord hanging from it and under load it flexed the socket forward far enough that it wasnt making good ground.
I fixed the ground, changed out the existing GFCI breaker for a 60A Siemens breaker that I bought from a link someone had posted on here on HBT for $42.00 shipped and planned to keep as a spare(thanks to the poster of that link). Fired everything up again and I was able to heat my MLT up to mash temps this eve.
Going to set up a full length water/starsan run to test/clean my vessels and pumps out over the coming weekend, assuming all goes well I will have to start thinking about what my first batch will be
The great news after all this is my father in law mentioned he had a 50 8 gauge extension cord out at the farm I could have. Now I dont have all the extra wire coiled up and the cable weighs next to nothing compared to that 4 gauge monster.
Thanks to all of you for your opinions and insight while I struggled through this. And very special thanks to P-J for the wiring schematic and controller advice(even if I couldnt follow it right the first time

).