is it normal in MG to have almost symptom free times or days when not doing much or to have several very exhausting, stiff days of discomfort followed by more activity than usual (which for me now seems to be gardening for a lengthy period or a few hour road trip)? This has become my life....

Yes, it is variable. By day, by hour.

It is possible to have several days feeling really exhausted, and then for no obvious reason a day when you feel fine.