The JMT actually doesn't cross Bubbs, so don't worry about that. There may be a few tributaries coming in from Center Basin or down from Forester, but they shouldn't be too bad. The only significant creek crossings will be Tyndall and Wallace Creeks. But that's what crocs are for!
NOTHING in the backcountry is kid's stuff, my dear. Believe me, I had that wake-up call this past weekend. You are already planning away, thinking of contingencies which might occur. Good on ya for that.
-L
