Hi everyone, looking for some input!

My boy is 5 and he loves to roughhouse and have competitions and play fight and seek the edge between acceptable and too dangerous. Daddy is happy with this, strong and tough and practiced at martial arts. I am not. I can handle a pillowfight (with a no-hitting-heads rule) and will race him, but anything more, and I get kind of scared to be hurt. He senses my discomfort.

He only has a baby sister, no brothers, and no socially acceptable roughhousing places or outlets (he hardly ever sees his cousins who also like to play rough - he holds it back for his quieter best friend and the placid local kids). And his dad works full-time. So basically he cannot get his fight on nearly as much as he feels the urge without getting into trouble, even if he really means well.

Do any of you have ideas on how to channel this energy? Without making him feel wrong/bad for wanting it?