Michael, there are some tomatoes that are just vulnerable to blossom end rot, no matter what you do, often the heirlooms. But the majority of the time it's lack of calcium that the plant can't uptake. Ground up egg shells are not something the tiny roots an uptake. It used to be that powdered
milk was cheap and it could be added to the
water. If you want to dilute milk, it won't help the ones that have it. It will help the forming tomatoes.
Boxed forms of calcium can take up to 6 months to be available to plant roots under perfect conditions, sometimes longer.
Compost tea from compost made from as many things as you can put in it, watered in,
should help the next round of forming tomatoes.
When planting, compost trenches or compost/manure mounds that are planted in and covered with crushed leaves or mowed grass usually provide
enough of everything to avoid most tomato issues.
You can just cut the bottom off and use the tops of the tomatoes.
An important distinction: Permaculture is not the same kind of gardening as organic gardening.
Mediterranean climate hugel trenches, fabuluous clay soil high in nutrients, self-watering containers with hugel layers, keyhole composting with low hugel raised beds, thick Back to Eden Wood chips mulch (distinguished from Bark chips), using as many native plants as possible....all drought tolerant.