That's scary. 1,000'? That seems strange it could drop that much. The physics would be interesting to see...
I've been rocked many times by 767s, 757, A330s, 747s etc. flying 3000+ feet above me. The wake slowly drops and drifts with the wind. It drops about 1000 ft for every 15-30 miles behind the aircraft. If you are traveling in the same direction and same speed as the aircraft making the wake turbulence, you can sit in it forever. It normally feels like light chop but when your only 1000 ft below, it can rock the wings on a similar sized aircraft significantly.
Over the ocean we use the Strategic Lateral Offset Procedure to lessen riding in someone else's wake. It is offsetting right 1 or 2 miles of track so you're not directly under and behind someone ahead of you. We only offset right and it helps even when their is a wind blowing the wake right.