In reply to Anna_wells:
Anna, you've received some atypically positive feedback on here for such an ambitious plan. Good luck with it. If in the planning you start to have doubts, you could always change (before approaching sponsors) to some thing like The Five Highest Peaks in the Alps (Alpine HiFive etc) in one season as this is a saleable goal that is much more achievable than the whole lot. You could go between them on foot, thus reducing the mechanisation and amplifying the journey.
Lots of sponsors, who are looking at what you can do for them, not what they can give you, are tired of yet more conditional 'firsts' and more are looking for the story behind the 'feat'. By paring back the physical objectives you can spend more time experiencing and relating the story behind the journey you and your friend are on.
This story starts now, actually it's already started, and threads such as this are now part of these kinds of stories. The travellers that engage, and keep, sponsors and followers are those that have an interesting story, well told, and involve those followers and sponsors along the way, from genesis to RGS. With Facebook, Twitter, iPhones this is all so much easier than outdoor communication just five years ago.
Concentrating effort on contrived 'firsts', besides being all a bit 1990s, distracts both participants and followers from the journey behind the effort. Ideally you could do both, but you only have so much time and energy in one day, and you will find that one is more rewarding than the other, in the long run.
You can still aim high, just in a different direction.