BER is a bummer and I've had my fair share. As you've read BER happens either with wide variations in watering and possibly a calcium deficiency. Once the fruit is affected, it needs to be picked and discarded. Last year, I tried the lime/water mix and felt it worked but I didn't use it this year (garden lime can be found in the lawn section of many hardware stores - usually for about $5 per 20 lbs).
I've found that BER often happens with early fruits and the later fruits are typically fine. However, this year, I've noticed that my Kellogg's Breakfast plants lost a high percentage of overall fruits to BER. Cherokee Purple is always hit or miss and the San Marzanos (plum variety) were affected as well. After doing some research, I've found that plum tomatoes can often be a victim of BER. My first fruits had BER but since picking those off, I've been fine. The Cherokee Purple, again is hit or miss as well as the Kellogg's Breakfast but both seem to be rebounding nicely.
Keep in mind that hybrid varieties have been developed to not only have higher yields but also have a resistance to various diseases. Heirlooms are more difficult to grow but some claim the taste is sometimes better (including me). You also have to keep in mind that some varieties work better in different climates. It really can be a balancing act.
For an EB or similar planter, I would highly recommend the Stupice heirloom. It's similar to an Early Girl hybrid but I think the taste is much better. Although the fruits are smaller - bigger than a golf ball, smaller than a tennis ball - they grow in clusters and do well in our climate and is an early producer. So far this season, I've grown two plants in an Earthbox and have picked about 7 1/2 lbs of Stupice tomatoes. This week, they're really producing and yesterday I picked about 10 tomatoes which are great for salads, sandwiches, etc. Now, they don't taste as good as the Cherokee Purple but I always have some on hand and some is better than waiting for those 2-3 big tomatoes to ripen on the vine. I'll also recommend the Black Cherry heirloom (cherry variety). This is by far, the best tasting cherry tomato I've ever had and the production has been good as well. They taste like mini Cherokee Purples, deep tomato flavor while maintaining a nice sweetness. The plants grow well here and although it's my first year growing them, I was pointed to them by other roof growers in Chicago that have grown them in the past. One note though, mine are over six feet tall already with no signs of stopping so you'll have to cage/trellis accordingly.
I hope this helps a little. I know its frustrating but it's been a difficult gardening year. Cool temps into summer doesn't help our tomatoes and everyone's garden seems to have been affected in some way. Keep sharing your progress, all info helps. Thanks.
"It's not that I'm on commission, it's just I've sifted through a lot of stuff and it's not worth filling up on the bland when the extraordinary is within equidistant tasting distance." - David Lebovitz