It's more like eight miles between Islip Saddle and Baden-Powell.
I'm not sure I would recommend it as an overnight backpack, as the only water is at Little Jimmy Spring. Even the Islip-Baden-Powell-Islip round trip can easily be done in a day. My wife, who has little hiking experience and only modest conditioning, was able to do it in about 8 hours, including lunch breaks.
"After the first glass, you see things as you wish they were. After the second, you see things as they are not. Finally, you see things as they really are, which is the most horrible thing in the world."
--Oscar Wilde on Absinthe