You would likely see an increased rear ride height, and experience a rougher ride w/o a load.
Air bags are a good solution. you can adjust the amount of air easily, and keep your ride and ride height where you want it. you can even get the set-up with an on-board compressor so you can adjust on the fly from the driver's seat.
Or there's the old school way, air shocks. I use them on my old '71 p/u and they work just fine.
Jay
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If you're not living on the edge, you're taking up too much space!