"An issue I still can't get past is that from album to album, artist to artist, the volume of bass will vary hugely. "
That's inherent largely in recordings.
Each recording usually requires unique processing in order to get all to sound a certain way. There is no single or easy solution. Pursuit of this will likely be time consuming at a minimum and fruitless at worst. Recordings are what they are, not what people might want them to be.
I shoot to avoid too much, fat or inarticulate bass with any recordings, even the most bass heavy ones. THen the rest will fall in line as best possible and usually quite well from there bass-wise. A sub can help but can also be quite hard sometimes to blend in by ear. Patience and good ears are needed!