My idea is that the RAF would eventually need a new trainer, the T.4 Harriers are not going to last forever. So the mod would be for a F-35B but it could be a trainer for all of the F-35 variants.
There is still a bit of work to do, for instance, the TF-102 cockpit could actually be a bit smaller so I could fit the modified 1/48 F-35B canopy. The TF-102 cockpit is 1/72 scale too. My plan is to use the 1/48 F-35B canopy, but it needs a bit of trimming to bring the height down to size, whereas the width once trimmed is about right. So what I would do with the styrene is to cut the rear decking behind the canopy off, I would then cut the top on the fuselage off along that line you can see running along the chine. Then I would sand the center mating faces of the fuselage join until it matched what I had trimmed off the canopy. I would then cut off the remainder of the rear end of the fuselage bits where I've shaded it.. This then would be mounted to where the existing bulkhead is at the rear of the cockpit.
Interestingly, not only does the TF-102 cockpit bits have a close cross-section, I found the nose wheel bay is right where the F-35 wheel bay is, I would then graft a F-35B wheel bay instead of the conversions wheel bay.
I had talked to Evan about this as I was thinking it out, I said to him I would extend the rear fuselage from just behind the wing trailing edge by adding in one more fuselage frame, to counter any cg problems. I studied a couple of photos of F-35's in production and guestimated the frames were about 3 feet apart, so adding the extra frame in the section where the fuselage profile seems to run parallel wouldn't be that much of a problem structural wise. What this would do is move the engine, tail planes and fin/rudders back 3 feet to counter the weight of the larger cockpit section. This also allowed me to use the bomb bay of the F-35A.
I would move the roll puffers back one frame space too, but leave the main gear where they are.
The pics below are what the link said was F-35 structure