I've also been trying to come up with a solution. Here's my latest contraption: I had installed a cell phone holder (I got for free at a trade show) on my vent. I use a case on my cell and wasn't crazy about it as I have to remove the case for the phone to fit. When I tried to remove the holder the clip stayed attached to my vent & I saw it had a ball joint that connects the holder. Okay, I thought, I might need to use that at sometime, I'll just leave it clipped on. Combined with this I had gotten a hook that was supposed to loop on a headrest to hold a bag of some sort. Again this was another freebie given in a store as a reward for buying there. I tried to use it but it doesn't work on Pacifica's headrests with the DVD screens on the back of the seats.
My pest control company gives me my bill in a little plastic trash bag. I've always used these trash bags in my other van - just hooked them on the gear shift lever. And BTW it does hook on the climate control knob but I didn't like that location. So I put all these little things together and the headrest bag hook fits on the ball joint of the cell phone holder and holds my little plastic bag. Don't know how long it will last, but we're going on a road trip tomorrow and will give it the full test.
Jeffersonton, Virginia ordered 2/28/2017, delivery on 3/25/2017 of 2017 Limited Tusk White Black/Mocha, Advanced Safety Tech, Theater Package, 20" Wheels, Splash Guards, and 3D Maxpider Kagu Black Mats