If Fleet wanted to use the Ramsey house for a few days, why wouldn't he just tell the Ramseys? Don't you think they would tell him to go ahead and use it? Seems they were close enough.

I don't see any evidence at all that the Charlevoix visitor was Fleet - - no strange car noted at the time - certainly not from Colorado.... and doesn't the suggestion that the intruder was Fleet also open up the problem of getting him out of Boulder and away without the rest of his family?

I think this is a stretch.