Weight Distribution bars are designed to do just that ... distribute the extra weight on the hitch from the back tires to the front, making all 4 tires have equal, or about equal weight riding on them.
To much weight on the rear tires and not enough on the front causes 2 things to happen. One, your headlights will be in the trees. Two, you will have very loose and light steering. The drive will make you feel like the front is floating and the steering is not as responsive as it should be. And actually, what you "feel" is absolutely right. You don't have as much steering control. Think of it as a bicycle doing a wheelie. Rear tire is doing all the load, and front has no, or little load, and you loose control of steering. And I suppose the third thing that could happen, depending on your suspension, the rear tires could bottom out with the extra weight hanging over the rear bumper.
You won't know for sure until try towing it.