Is it legal to have 2 adults and 3 kids living in a 2 bedroom trailer in Wisconsin?

The answer to your question is that in Wisconsin, there is no  statutory provision or specific case law that addresses living conditions for minor children. The court would have to consider all the facts and circumstances in making a decision whether their current living arrangement is hazardous to your children's health and if so, to modify that parent's placement schedule to be more day time situated.