Looking for an indestructible crankset

I have one consistent problem while biking, and that is broken crank arms. I ride a single speed with a 52t chainring and a 15t freewheel. I lift and weigh between 190 and 210 depending on the month, and the only way to climb long hills is to stand and mash. I've tried various brands of cranksets, but broken crank arms occur roughly twice a year. One unexpected break after a long ride caused me to veer into the road. I'm up to 7 broken crank arms over the past 4 years. All have been 110 BCD square taper cranksets. Every failure has been on the non-drive side, and metal fatigue is always the failure mode. Two failures have occurred due to cracks starting from the square taper corners, one has been a failure of the pedal stem eyelet, and four have been broken clean in half. I'm well aware that my gearing and riding style are the cause of the damages. I'm essentially looking for a bulletproof crankset. Whether it is aluminum or a solid hunk of steel. The goal is durability, weight be damned.

Does anyone have a suggestion for an "unbreakable" crankset? If I'm left with no other options, I'll have a local CNC machinist mill out something indestructible.