Dear Xavier
The solution from Neil will work but appears very complicated and delicate.
I assume you have the lens adapter for the 5100, to get you out past the extension of the lens, and the step-up ring to fit the 52mm largest DCA top plate.
I suggest you google-up "lensmate" and Richard Freniac's clever accessories. (Or google "camera release canon g9" and check out Don Ellis's pictures and other subsequent comments)
I have the Canon Powershot G9 with adapters to a CDA onto the Swarovski 80HD. Freniac does a neat clip-on to the G9's shutter release/zoom button, into which the cable release is screwed. No arms, levers, safety pins etc.
Write to them. They may make, or be able to make, something similar for the Coolpix. An alternative you might suggest would be for them to make a stick-on handle grip for the 5100, as they have for the G9, with a built-in extension bracket that goes over the release button and takes the cable. This would allow you to zoom easily.
It's a pity everyone appears to have dropped remote releases, without which good digiscoping is impossible.
However at least it make us look for alternatives, and we do not have to put up with the terrible, tiny, vulnerable jacks and sockets of the Coolpix 995 and 4500.
An infra-red or wireless would be nice, but a good old -fashioned cable is not going to go wrong in the middle of the jungle with a lifer in your sights.
regards
Steve Cook