Lone,
We can actually both be right here - there was certainly a great deal of political attractiveness in 'Joint' solutions' (the F-22 was originally pushed as joint programme, with Lockheed claiming it could operate off a carrier!), which the programme architects certainly wanted to exploit. The DoD sources I knew (fairly highly placed) were ready to share with the UK the very large amount of technical study they had done to indicate that a single engined single seat solution was practical. I'd suggest the two came together to produce the programme.
LO, again I'd like to suggest that we may both be right. The F-35 has a spec sortie to be able to deploy to a 1500 foot bare strip, shut down and wait orders to launch for a sortie, do the job and then recover to the ship. You might think that's a rubbish scenario - hey, we can all have opinions, that's a good thing. But the fact is that you need just 1500 feet to 'operate' an F-35B in that particular scenario. More if you use another one.
I'm glad you're interested in the improvised-base ops demos - so am I. One thing to note, that builds on JF's excellent post. This aircraft has a level of stability and control in the hover and transition that is a whole generation on from the Harrier. There are a variety of potential landing and takeoff modes that the test team are working through, with the able assistance of some excellent Brit TPs. I'm sure that the USMC will find ways to exploit them.
On the prepared surfaces stuff - I had a great time managing a whole set of surface erosion trials at Warton. These were far beyond anything ever attempted for Harrier, and delivered a ton of data to the programme. happy to give more info over PMs if anyone's interested.
Best Regards as ever to those fine STOVL folk
Engines