The part of the GRT you'd miss by doing 1 or 3 isn't its most enticing, unless you're really into looking at forests from the inside (which sometimes people from the southwest are!). A slightly longer variation that would incorporate most of the highlights of 1 and 3: follow 1 to Daisy Farm, then ...

I am planning a trip to Isle Royale at the end of September. Due to the frequency of the ferries, my main plan is getting on the ferry at Grand Portage (to Windigo) on Sunday, Sept 24th, do an across island hike and get to Rock Harbor to take the ferry back to Grand Portage on Thursday September ...