I got curious and started googling the extension services. 
They recommend a foliar spray of calcium chloride to control blossom end rot in established plants. I used to use the stuff to curdle tofu, but there are issues if too much of it gets into the soil and its use in "organic" agriculture is iffy (safest and most accepted in just that application, though).
Maybe try whirling some eggshells and water in the blender to use as a foliar spray?
Just a thought.
Another thing I read is that plants that have a lot of fast, leafy growth are more susceptible to blossom end rot, because nitrogen is involved as well. Maybe that's why your one variety is affected?
Speed comes from what you put behind you. - Judi Ketteler