I made slices, and they were (and still are) very crispy. Not mushy at all. I don't know why yours would be mushy, perhaps they didn't ferment properly for some reason.
Why don't you just use a small amount of cucumbers and make one jar as an experiment. Or make two or three, but do different amounts of salt (and whey if you use it) and make a note of what you did so that you can see what turns out best.