I don't want Ralph to come back and say we hijacked his thread and tried to change his method.
So go for it with your current setup, which is in line with the Way Beyond Monochrome testing instructions.
Mask your test wedges and make the best lens shade you can.
Expose the strips for three or four more stops of light than you did last time.
Hopefully, you will find N somewhere near 12 minutes and you will have some densities near 2.0
Flare was messing with your toe densities that were supposed to be under 0.1.
Underexposure was keeping your dMax under 1.0 when it could have been 2.0
Because you are not using "modern" lenses, you may still have higher toe densities than Ralph, but it will be a model of your camera system.