warning: total manufacturing newbie here

But i would like to ask.

How much effort/legal/heartache is involved in building an after market add-on for commercial vehicles?

Some comforting assumptions - internal customers. no sales. - good software talent. can work around anything. - almost no moving parts - mostly electronics - can accept cost overrun on the components - each unit is >$10K - gradual scaling to 1000s units/annum - daily return to hubs if needed