When the weather is good enough (as it is not in New England winter) I carry a Deuter internal frame loaded with bottled water from a store. A case of pint bottles weighs 24 lbs., about what a weekend pack should weigh if can ever get my load down to where it should be.
I do one mile when I am somewhat busy, 3 to 5 miles on the rare occasions when I can spare the time.
I bicycle when I can and strangely I find I get more of a workout from that than the pack.
I do think the pack idea is a good one though.