Soft water is [subjectively] good for a stout anyway, as long as you aren't going for a super dry, Guinness style. RIS, big and smooth - soft all the way.
So, no, I wouldn't worry about water salts. You need to have a good idea about what your mineral content is to begin with to do good adds, anyway.
Primary: Agave Wheat
Secondary: What sorcery is this?
Bottled: RIS, Wee Heavy, Oaked Wee Heavy
Kegged: Pumpkin Ale, Hopped Cider, Heady Topper Clone, Coconut Vanilla Stout