Honestly, there might be options available, but draining a tank through a fuel line will take a similar length of time to simply burning gas, not to mention the extreme danger in siphoning or draining gas due to risk of static shock around highly flammable vapors.
Most options available will simply cost you more money or time. The safest, and likely cheapest option available will be to simply burn the gas. This leaves you with the two basic options you outlined in your original post: idle for hours, or drive around. Lets look at the pros and cons of each option:
Idling: PROS: You don't necessarily have to be in the car; Safe; easy. CONS: Takes HOURS, like probably 15 hours to drain what you need, depending on your tank size; Slight risk someone might yoink your car while its idling.
Driving:PROS: MUCH faster; Safe; easy; you could get other errands done while you are out; have a friend do it. CONS: You or someone else needs to be in the car.
Now if you choose to idle, you could speed up the time a little by turning on the air conditioning (if equipped), and turning on every electrical thing you can in order to put some load on the engine from the compressor and alternator.
If you choose to drive, the best you can do is increase the aerodynamic drag and weight as much as safely possible: load it up, borrow a big boxy rooftop carrier, tow a trailer (if equipped), or all of the above.
Best of luck!
