it can be a lot of fun being a "guinea pig" because not only do you help yourself, the doctors, researchers...you eventually help other people by proving this is a viable thing.
Leanne is only 9 this year and some of the things we've volunteered for...
the "robot legs" study.
alternative input devices for computers/robots/cars.
training for new physiotherapists.
at about 3 1/2 years old she proved that younger people have the cognitive ability to control devices. She was driving a power wheelchair at 4 years old...the youngest person they have ever seen or even had considered trying. They had to actually order her a special powerchair to fit her because they normally never even thought to try kids younger than 7 or 8 since that was the fit for the normal "smallest" size.
Even when she goes in for surgery she always allows the doctors and nurses to bring trainees along, Even asking if she's going to be bringing more people. She loves that she's helping other people.
Guinea pigging for the government can open lots of doors for funding, especially with the mainstream forces like the air force, and army. If anything just outright ask the DARPA coordinator if he knows of any funding available to help pay for a modified van. I'm sure if he doesn't, he will find someone who does. They are "that way" if you know what I mean.
Governments are not particularly forthcoming with funding...going so far as to not offer you anything, not tell you anything, and bury any info regarding it. So unless you know about it, and specifically ask for it, you won't get it. (which is really annoying to me, but i get it, they want to save money)
But having an inside like your DARPA coordinator, he can find out and let you know... and then you can apply for it.