Automobile trips usually allow for more gear and a better variety of panel options. I like to keep a plastic tote box in the back of my CRV. In this box goes all of my gear with wet panel carriers, turpentine and extra clothing in case of changes in the weather.
I keep my gear in a backpack. I find the after market packs are better than the ones from the pochade companies but do your research and find a pack that is comfortable for you with all your gear in it.
The bottom compartment of the pack has my brush washer, garbage bags paper towels bug repellant and sunscreen.
The Pochade box with all my paints and brushes go into the top compartment of the pack.
The tripod and lightweight wet panel carrier strap to the outside of the pack. This setup allows me to hike for miles if need be with up to ten panels and all of my painting gear.
The bottom of the tote box has extra clothing for extreme weather, paper towels, water and turpentine. I also have a wet panel box to put my finished paintings in.
My backpack goes on top of my other supplies and I secure it with cargo netting. Using cargo netting over the top of the tote I can pack things higher than with the lid on and still have them secure.
The plastic tote helps keep everything together and keeps me from getting paint all over the car.