Tire pressure while towing; better to increase or decrease?

Not sure if it makes much difference but was wondering if someone has tried increasing or decreasing tire pressure when towing heavy loads--7k lbs range?

Grip, gas mileage, ride comfort, safety...?

In general yes you do want to air up the tires when towing, because with the weight of the trailer on the rear it will cause the tires to over heat. But never ever go over the max PSI of your tires.

Since you are nearing the max weight the AV can tow I'd recommend you get a towing E load range tire.

Consider this if the trailer is 7k then add the weight of the passengers, luggage, gas etc that is what you are really towing

I agree with what MS03 2500 wrote. I have a max rating of 44psi in my BF Goodrich tires and usually carry about 40psi and 42psi when towing. Consider the increased pressure when heat builds up.  In south FL especially during the summer on asphalt road surfaces the tire pressure can increase 2-4 lbs so I factor that number especially when towing.