This really is an ambitious project. I spent quite a few years building custom cars and I have to agree that for the purpose they're aiming at what they're doing makes more sense than trying to outfit an existing vehicle with their tech.

For example, I worked with a company named "Mobility Engineering and Development" outfitting Ford vans that C-4, C-5 quadriplegics could drive while sitting in their wheelchairs.

Ford didn't redesign those very often so it was a very good choice for that purpose, but it would be a nightmare to have to redesign what we were making every 3 years to accommodate a new vehicle design produced by a 3rd party that had no interest in what we were doing with them.