So you've read this whole thread through and decided something MUST BE DONE ! The telescopic ladder is too expensive, and too difficult to fabricate but an old aluminium extension ladder cut down should do the trick.
Comes the day that it is put to serious use - the MOB (who does not know the device's pedigree, perhaps it's that fool off "the other boat") pulls down a bit of ladder, enough to get a foot on - and then guillotines the fingers off the hand(s) gripping a rung further up. OH NO! can his day get any worse? Well yes actually, because, attracted by the smell of blood in the water........