I'm about 99% sure that venting solvents is against federal law, I know for sure that you can not legally do that in Florida. Not that you will get caught but printing operations are on the radar. I think there is a misconception about what defines hazardous waste as well. its not just toxicity. Flammable materials are considered hazardous and since it is against the law to intentionally vent solvents, your waste stream will be deemed hazardous. You can argue your case that you dried it out so it is not hazardous but you are admitting to another crime with that.
If you own your property and go to sell it, the first red flag in a phase 1 will be how you disposed of your waste. If you have nothing showing proper disposal, the assumption will be that it is in the ground or down the drain. If you are on septic, you are guaranteed to be getting test wells dug there. Anything that shows up in a phase 2 is required to be reported. If the DEP/EPA ever comes in, they can force the same thing on you. Get a 55gal drum, spend $250 a year and keep your paper trail. It is money well spent.