No answers, but I'm interested as well
I can't provide any assistance here, but would love to learn more about this if you find anything.
Got have the hook -- if you want the green!
Corporations of any type rarely sponsor folks to go on road trip lark. You have to have a marketable hook that matches with one of their marketing goals. Do your research -- see if a local company would be interested in securing some national exposure. RTA has worked for the ACS -- but road promotional work leaves 0% of time for exploring or going to national parks, etc.
There are a number of resources for funding -- but you should expect to spend 10-14 hours per day in support of the commercial/charitable project.
RTA