No you cannot fly outside the 180 minute range ring (unless an emergency, although it'd be hard to imagine one).
Good explanation CS, concise and correct, however one point that needs clarification is that you can deviate around weather even if that takes you beyond the EDTO range circle, but you must return to within the range circle ASAP once the weather has been avoided or as you quoted in an emergency the PinC can do what is required.
Beyond 180 is a whole different ball of wax!