The Skyhook idea was not " barking ", I saw it being done on Dunsfold's trial crane many times - did you ?
I agree it would be tricky at night in a lumpy sea, but with suitable guiding low intensity lights I ( not a pilot ) would still fancy that compared to 'crash landing' a Phantom or similar on a carrier...
Harrier Chief Test Pilots do not come up with mad ideas...the rubber mat & vampire tried by Eric 'Winkle' Brown you mention has always struck me as exactly that !
The only real drawback with Skyhook was if one went whole-hog on the concept, it might involve deleting the undercarriage & it's strengthening, to allow more weapons/ fuel carriage in the hover ( as it is, more than one Harrier has done a VL without wheels, and a certain display pilot did a magnificent RVL touch & go gear up, to the delight of many photographers if not his boss...
However that's going by brochure figures ( a problem the Harrier had was that thrust/weight is what everyone will look for first, while its traditional or obligatory to keep max thrust a secret ) - I've seen FRS2's, as then known, and a lot heavier than an FRS1, hover for quite a while, carrying ' impossible' loads...When I asked someone in the know about this, he grudgingly agreed there was a lot more thrust available than advertised.
Perhaps John Farley or Michael Pryce, if by any chance reading this, might like to comment.
I do know the latter mailed me performance graphs of the Pegasus, which went way beyond ' official ' figures.
If you should happen to put 'Harrier history' into a search engine, then scroll down to 'Harrier Testing' there's a little more on this - I checked figures with M.Pryce as I wrote it ( subsequently to be mangled grammar-wise, and a couple of mistakes by self - it was Duncan Simpson, not Neville Duke who tried to save Chuck Rosberg - but he reckoned I was on the low side re. max thrust ).
As you mention stability, I play with small yacts a lot of the time, and know what you mean; I think a Sea Harrier would be tolerable ( probably with limits as to the conditions ) but an F-35 will be a different matter, twice the weight, though I'm sure money will be thrown at it so things like RVL's or indeed skyhook will be quite feasible in service.
Maybe the trimaran warship project, Trident, had this in mind ?...
As for SCADS, it's a great idea, as long as the fit includes CIWS, the only drawback being the short runway and no ( or rather, difficult to manufacture as a bolt-on quickie, Ski Ramp ).
There are ways around the latter, as the Royal Engineers could tell you.