Punch bags for sensory release. Good idea?

Our son is seven/non-verbal and generally doesn't have too many behaviour issues but recently his been getting more sensory seeking. We've been doing sensory circuits, brushing, joint compressions, etc. during the day but at bedtime it isn't enough and he goes into an sensory seeking overload and is hitting/kicking basically until he runs out of puff and has got it out of his system. Then he just gets back into bed, settles down and goes to sleep.

We were thinking of buying a punch bag for him to get it out of his system instead of directed at us. Has anyone had any success with this and if so can you recommend a good bit of kit? 

Thanks in advance, Neal