You mean like this:
It will work fine. If you think about it, the pin weight on the fiver is at least 2000lbs. It takes the force of that 2000lbs to compress the air bag as you are driving down the road. People walking around inside the fiver don't begin to have enough weight to compress the bag. Even my kids jumping around all over the place don't move it one bit. That being said, the pin box stabilizer is not going to eliminate all the movement in the fiver. I think it helps but as others have suggested, you may look into the JT system. It seems to get great reviews.