We are seriously considering completely leaving the roof behind and just having a tonneau for when parked, and yes, the spare wheel is an issue, but I'm hoping to solve this using a preventative sealant in the tyres before we leave. I heard some great test results of it whilst working for Land Rover a few years ago...just trying to find out which is the best one!
Good tip about the king pins and the springs, we have the support of Russell Paterson Morgan in Scotland and hopefully he'll be able to sort us out with the right stuff to use.

Tony.