I designed the boards and wrote the firmware for boards where I had to do the work. I had a subcontractor build the boards, so no need for fancy tools. Over a 5 year time frame, the only hardware failures were one electrolytic cap and one temperature sensor with lightning damage. It was a pretty high G environment on a coal carrying railcar.
That is indeed a high-G environment. Sounds like interesting work.
I also design boards and write firmware. There was always work for me. Even now I have some clients that want to keep me busy. It seems they can't find the hardware/software/system design in one place like me.
Lightning. My favorite.
I've used a bushel of uP's, lately I'm leaning heavily on ATSAM ARMs. I used ATMEGA devices for many years, sprinkle in PICs and some of the wonderful old stuff like Z80s, 6800s, 68000s, and 68HC11s along the way.