Hellobee Boards

I love these:
Kick Mat Auto Seat Back... https://www.amazon.com/dp/B01N4N4AGC?ref=ppx_pop_mob_ap_share

The pockets are big enough -most other similar products have like 9 pockets, but all so small, so not everything fits. More mental work.

Our 4 pockets are: clothing, snacks, little toys, and cleaning (tissues/wipes/sanitizer)

We have one for each kid, one behind the driver and one behind the passenger.

Also, at the foot of each kid, we have a box of books. Usually they are they books we own that I DON'T like to read or ones with lots of pictures to look at.

I always feel like I have so much stuff in the car! I do try to keep it seasonal - like I don’t let them keep blankets in the car in the summer and then I can put away the picnic and water play supplies once it gets colder.

I’m a huge fan of zipper pouches to organize inside a big bag. I’ve found some cute ones in the target dollar spot! My purse is this way (in lieu of diaper bag) and it works in a structured tote or bin in the car also. I would keep the sunscreen in the wet bag, keep the wipes and hand sanitizer with the diapers ... basically just try to keep together the stuff likely to be used at the same time. Then you can just grab a zipper bag and go vs digging. I also now have a bag of random baby stuff (bib, placemat, hats, etc) so it’s just a lot of junk

Some of that stuff I'd keep in a go bag in the house, like water bottles, sunscreen, wipes, snack. Those all fit in a really lightweight backpack that we keep in the house and just grab when we go. Wipes dry out in a hot car anyway.

In my car there are two compartments in the trunk that hold a seasonal change of clothes and a stock of plastic cups. Toys float around the back seat but I regularly have the kids bring one back into the car. Blankets stay in the house and only go in the car in the winter.

When DD was rear facing I had a collapsible tote on the floorboard behind her seat. I was so bummed when she turned forward facing and I had to move it. I moved the tote to my truck and used a bungee cord to hold it to one side so it doesn't move around. The tote holds: a first aid kit, paper towels, and a full size towel. There was a lot more in it when she was little, but I limited it to what could fit in the tote. I keep tissues and hand sanitizer in the center console up front with me.

Then like someone else said we have basically a "go bag" in the house that we grab whenever we leave. Because it comes inside every time it is always based on current needs. Either DH or I can grab it and put it in either car. This time of year it has: change of clothes for all of us, sunscreen, bug spray, wipes, and extra sunglasses for DD. I add a coat, snacks, and water bottles in the morning if we will need them. We don't really bring toys regularly only for long drives.

In winter the blanket goes in her seat if she is not in the car and on her if she is. I also have an extra collapsible tote in my trunk if there is more stuff that needs to be contained.

I would be careful of hanging seat organizers on the back of the front seats. In newer cars most front seats have airbag sensors that can be messed with by hanging anything on the seats.