Peter,
you might consider taking the Rockwell Pass from Tyndall Basin into the Upper Wright Lakes Basin. From there you go up Mt Tyndall. It has been over 50 yrs, but I climbed Tyndall from the upper Wright Lake and do not remember any serious problems as it was indeed a Class 2 climb. You mention climbing down Tyndall south ridge to Wright Lakes and then to JMT. By going over Rockwell Pass you could leave the heavy packs at your campsite and go up the SW ridge with only a day pack and return to your camp. From there you would continue down to JMT. This would avoid carrying heavy packs up Tyndall and still keep you on your intended route to JMT.
That certainly is an option. The camp site location will be a matter of when we get there. Tyndall is a bit rough for what I would want to do with two teenagers in tow, but at that point of the trip we should be pretty well aware of what our limits are, given we'll be traveling cross country for much of the Sierra crest before we get there.
I need to start another thread for our route, since I need to pick some brains about some route segments I am contemplating.
