You could start a small machine shop for under 50k if you have the land and building already. You don't need brand new machines, just like in the heavy equipment construction world. If you don't use some of the crap coolants, and have a nice evacuation system there is zero mist problems. Diesel exhaust leaks in marine and or site applications, as well as any cleaners used will rival and beat the mists from the good coolants used in machine tools. Personally I have had enough traveling to jobs and fighting traffic. Working on mission critical machines like a Genset, especially for the fishing industry could end up with huge law suits as well as the hospital emergency genset world. For that matter most Gensets fit into the mission critical role.