What if you start preparing a sponsorship dossier? It could also help you to understand in a more objective way your strong and weak points.

By sponsorship dossier I mean a document to be sent to your potential sponsors where you introduce yourself and explain the goal of the trip, particularly what makes it so special (you are a professional photographer and plan to witness the reality of the scarceness of water resources in the old Silk Road, see how it has changed over the centuries, the future challenges or if it may be the trigger of future conflicts, whatever your point is or you can create! Or you’ll follow the same route as Sven Hedin, etc.), maybe the NGO you are supporting (that’s appealing today, say one digging wells? Sorry if it sounds selfish or superficial), explain the vehicle, the exact route (pics, maps, etc), your previous works and trips to prove your expertise and ESPECIALLY the exposure and business opportunities for the companies sponsoring you (stickers with logos on the bike, appearing in the media; banners on your website, which as many visits; the chance to test their products on the way, etc, relating to the case, go for companies related to water industry; I mean companies of a different field, as an alternative to motorcycle gear, where you would need a bigger motorcycle exploit to find sponsors), tell the contacts in the media you have and the interviews on radio, tv, articles in papers you have already agreed or given/done about this expedition, or your pre-agreement with a publisher, etc. To keep in mind, PR departments send the newspapers articles ready to be published, so that papers save the work of preparing them. The condition is to write objectively (I lived that a lot when I worked in the olive oil industry, sending news to the papers telling we had won a prize to the best olive, etc). Actually, all the people whose trip appears on the paper as “a couple sets off to Australia on their old Citroën 2CV in a life-changing quest/to raise funds for Save the Children” are ALL sent by the couple to the media. They need/want exposure and they create it themselves. Of course, it is not that the paper found out that this good fella planned a cool trip and the journalist called him to have a interview, it is the other way around. Or the sponsor's PR deparment will do.

So, the sponsor will take it as business, therefore you’ll need a business approach, formal, showing business opportunities, so this dossier, articles, etc will be a must for them to take your project into consideration. Needless to say that then the trip will become sort of the job which will imply obligations, as mentioned before. As TonyP said, you’ll trade your freedom/rest for the benefits of the sponsorship. In fact, I guess that having that support may also be considered as a personal success, since you are able to believe in you and your project. In your case, Pros: economic support and you will force yourself to work hard because of your commitment, which may be good for your future book. Cons: you won’t be totally free any more, which may be especially hard if you only get 1 sponsor, but still have the same obligation with it as if you had 20.

Just my understanding and how I see it. Hope it helps.

Esteban

EDIT: I've just visited your site (I missed the link) and seen your banner of "Lifesaver: working to end water poverty". How come I thought the same about water? I found I HAVE SUPERPOWERS!