I think some tomatoes are more likely to get BER than others. You might want to try a different variety of Roma; maybe a hybrid variety if you don't mind hybrids. You could purchase just a few plants and do your own experiment this year.
Try mulching. If you don't have any, rake up grass and use that. You only have to surround the bottom of the stems with it.
When the season is over HEAVILY mulch your garden bed before you put it to sleep for the season. Everybody would think that my old farm property would have great soil, but it didn't. 100+ years of somebody else using the soil depleted it to clay. I have been mulching from my horses and chickens for many years now, and it takes YEARS. BUT, if you mulch in the Fall, it will have plenty of time to break down for the 2020 growing season. I have very little blossom end rot bc of this. Just some "food for thought."