It looks like your Mandy Hollow tomatoes are at the explosive growth stage. It always seems like they creep up to 18" and then, BOOM! Up they go. Mine are ready to start ripening, but they have had some watering stress with dry spells and then heavy rains. I've had about 20 tomatoes in various stages of growth with blossom end rot. I felt around most of the tomatoes and they are firm and well-shaped on the bottom. I think this is not going to be a long-term problem. It is becoming very hot with temperatures in the upper 90s and maybe a couple of excursions to 100+ over the next week. I ordered some 40% shade cloth today to put over my trellis nets. I'll put it over in the afternoon and roll it off in the morning when they need light. I'll use bamboo poles like fishing poles to roll it up on. The searing heat is just too much for tomatoes. Hopefully, my indeterminate tomatoes will keep setting fruit if I shade them. I'm going to shade my bean plants too, but with a different method.