Attempting to get a seasonal job, year after year, for just 2-3 months a year would be difficult.

My wife is a former school teacher and she spent a considerable amount of time planning and working on things for the next school year. If teachers are expected to all work over summer break to make ends meet then their performance will suffer.

I'd argue that a better approach for teachers and education in general would be to move to more year-round schooling.