Alright. Ive given this some more thorough thought, and I can only see 2 ways of achieving what Im after, and both are far more complex than any reasonable person would deem necessary, but then I do like land rovers, so Im sure you lot will understand.
Option 1 - A completely custom pop up roof, leaving the rest of the disco relatively as-is, so it can be used as a 7 seater, or a 5 door with a decent boot, or a 2 seater with a big boot. O think the easiest way to do this is to buy a pop up roof tent from a campervan, and graft it into the discovery roof. Possibly using the cut out bit of the roof to replace the van roof, or not, depends on what works best.
Option 2 - The chop. Chopping it to a single cab, with maybe some storage space behind the seats, and extending the chassis. Personally, I would make it a flatbed, with all the land rover related stuff going into lockable boxes under the flatbed (i.e. tools, spares, recovery stuff) and then have a demountable camping thing, with all the camping stuff. Probably not the thing that looks like a cut up caravan tacked onto the back of a pickup, more like a steel box with a bed in it, with some draws and a bit of space left for camping chairs, firewood, whatever. Even better if in flatbed form it could be made to accomodate a small car, but that wouldnt be a priority.
Both are very versatile in very different ways. The extended one is of course no use in carrying more than 1 passanger, but is better at everything else.