Small companies are much more like families than like work projects. There is a lot to be said for this. I would be a bit careful about engineering to stressful a situation at first, often with much less stress you can get hints at what the response will be and test those. Full on stress can bring out things you don't expect so you need a good backup.

At a former job we hired a person I knew from a former company into a job that was too stressful for them and it brought out some addiction issues the employee felt they had conquered. Turns out not so much. It was challenging but we got the employee help and back into a stable situation, but it was not the experience we had expected or planned for.