Tim
I made a strap out of seat belt webbing ... readilly available in any junk yard for next to nothing...but as a landscaper I go through about 1500 feet every year for various lifting odds and ends So I buy it in bulk...
I hand stitched my loops with 65lb spectra. as other has said when the water is low getting the loops on the boat and maintaining tension to keep the loops in place can be a struggle. if you make your strap and its too long. you can always tie a few knots in the strap to "shorten" it up...
I like the pipe/tube carrying rack, but its not real "portable" nice thing about the strap is that you can put it in your pocket or drape it around your neck and you've always got your "sling" with ya. No having to worry about grabbing someone else rack. I do notice that the racks end up piling up near the put-in-take out location and can become a potential tripping hazard for those of us who still drag our knuckles while walking...
also when done for the day I wad the strap up and drop it under the deck when I pull the battery out for the last time...