Hi again, Ewan.
1 how much of the young mans body will it eat ?
It will eat almost all the flesh of the young man's body.
2 would the large komodo dragon be able to swallow whole the area in the tight swim trunks + the tight trunks?
Yes, the dragon would be able to swallow whole, the area in the tight swim trunks, in addition to the trunks. It can open its mouth really wide, due to its loosely articulated jaws, flexible skulls, and expandable stomachs, which allow them to swallow smaller prey whole (like goats).
3 How long would digestion take in good conditions?
Due to it's slow metabolism, it could take up to a month for full digestion.
4 what if anything would be lefy on the beach ?
The skull and perhaps a few bones would be left on the beach.
5 Would it be able to digest the tight swim trunks and what was inside ?
It would be able to digest what was in the tight swim trunks, but the trunks themselves would be ejected along with teeth, hair and anything else undigestible, when the Komodo dragon regurgitates something called the 'gastric pellet', which is covered in foul-smelling mucus. After regurgitating the gastric pellet, it rubs its face in the dirt or on bushes to get rid of the mucus, because it can't stand the smell, either.
6 How would it get rid of any undigestable items and would it be recognisable ,if someone looking for the guy came across it ?
Same as answer to #5 and no, the undigestible items would most likely not be recognizable if someone looking for the guy came across it.