If you approach any national or regional firm for sponsorship, one needs to be sophisticated in developing a clear written purpose and plan. It would have to be a small business proposal. These firms get alot of other companies (not individuals) asking for sponsorship also.

You have to have a compelling story/theme why a company should support you with their $$$$ for a bike ride...when many people now are touring solo on their own across Canada or U.S. compared to 20 -30 years ago.

If I were you, forget about the sponsorship route for now and focus on a route/way that will allow you to camp as often as possible.

Or consider working for a few months..a year to gather enough money. Then do the ride.