Here's a few ideas -- cheap velcro breakaway gym pants so you can easily get to whatever you need to without pulling his pants down; box of thin latex gloves and alcohol wipes so you can keep things sterile without easy access to a sink to wash your hands; an empty gaterade bottle or something with a tight lid so you can empty the bag (if necessary) without dragging him into a restroom; if he's using the larger overnight bag, maybe have a cheap dollar store plastic bucket so it doesn't have to lay on the car floor; OTC antibiotic gel to lube the catheter tube by the penis (a recommendation I got from my health care team); a trash bag and roll of paper towels in case there's any spillage if the catheter tube catches and pulls out of the bag; a disposable pad or plastic liner for the car seat so if there's an accident the seat doesn't get drenched; a clamp to clamp off the catheter tube if you need to change bags; I'd probably travel with the overnight catheter bag as the day bag fills up pretty fast; as my health care providers told me frequent stops so he can walk around to reduce likelihood of blood clots; as others said, lots of pillows and such so he can get comfortable; water and whatever meds he's prescribed so he can take them on schedule; maybe a change of clothes if he does have an accident and get's soaked; some kind of screen or paper and tape to block the sun if it's coming in the car window and shining in his face. The only other comment I'd make is that my wife and I had a 6 hour drive to where I had my surgery done. We also struggled with whether to drive home or just stay in a hotel next to the hospital for the week the catheter was in. We finally decided to just stay there. But the cost was affordable and the deciding factor was it took the pressure off my wife if something had happened (either medically to me or a car issue on the drive home). Nothing did happen, but we don't regret staying at the hotel. I think staying just another day at the hotel might be advisable as you're adjusting to the routine of having a catheter and frankly just giving yourself some time to see how he's doing. Just my 2 cents. I am not a medical professional nor do I have any special expertise in all this. Best of luck!