yeah I know the feeling Martin, that walk out is a killer for me to ,too fat and I was a smoker so that didn't help.
seen the view and yes it is spectacular, the easiest way might be to take an inflatable craft in to the needles and paddle up river or up the dam road do a day trip (or maybe 2??) down to Engadine, just need someone to collect you at the end, Or get dropped off at heathcote rd and climb down. whatever way i reckon you will need very light kayak or inflatable + gear, as there seems to be a lot of long sections without much water (from Google Earth)
Chris