Completely off the wall weekend I looked into a few years ago but got funny looks (again) when I suggested it. Colonsay ! There are about twenty or so 'MacPhees' - hummocks of two hundred feet ! - which can be done in a day. Distance nearly 20 miles. At that time there was also a bunkhouse. I will do some up to date research. Ferry times I believe were do-able at that time. Watch this space !