I was pursuing this issue the other day, looking at Home Depot for something to use to regulate the voltage, rather than to turn it on and off. I looked at the light dimmers, but the highest-rated one I could find was only 600W, and that's not gonna work. I talked to an electrician friend of mine, and he said you can get 1500-2000W or so rated dimmers, but they're up there in price ($100-$150). As I looked around HD, I found a "mechanical" electric baseboard thermostat. By the way it looks, it's just a high wattage dimmer - no temp settings, just higher and lower. Fortunately, my smoker doesn't get overly hot, so I don't need one, but it's an option for anyone who might need some sort of control over their temperature, but doesn't want to worry about not having consistent smoke.
Jim