MG
I would start by contacting the organisers of
Aero 2007 and get a list of exhibitors.
They had ~ 1 massive hangar equivalent full of these things. No idea how many of them can go on G-reg but they must all be EASA approvable.
As for composites v. aluminium, from the purely material point of view glass / carbon fibre will not be affected by weather but can be by UV; I will leave it to others to comment on whether the gelcoat used on these planes does the job.
Aluminium is OK if properly corrosion proofed and this is something that has to be done exactly right otherwise the stuff just rots.
I think you will find that most new-buy modern-design candidates for your spec are composite.
I'd happily fly a composite and have done so. The only real issue is that if somebody had dome something dodgy and "not quite" bent it, and kept quiet (a very common occurence in this game) the damage may not be visible, whereas with ally you can usually see ripples or other distortion on the external skin.
What rots quickest (and most expensively) are avionics/electrics, and you would get a decent cover for that reason - a few hundred quid.
Rod1 - is the VLA requirement necessary here?