How often to stop (moving w/ cats)?

We are moving in a month, the drive will be 14+ hours and we are going to do it in 2 days.

I've taken both cats on a 5 hour road trip in my VW Jetta and they were fine. I didn't keep them in their carriers (dangerous, yes) and had a litter box up front. Chloe actually used it a few times, she was really young at the time. She used it while the car was stopped and while it was moving.

This time, I do want to keep them in carriers. I just don't know how often to stop to let them use the litter box? What do you think?

I'd stop and let them out for 10-15 mins every 5 or 6 hrs. Usually if you can wait to feed/water when you stop for the nite or a long time for dinner, then you don't have to worry about them using the litter pan.

When we drove from Florida to California, I don't think either cat used the litter box in the car at all. We drove about 36 hours straight, and if I remember correctly we stopped only for gas, and let the cats out of their carriers during the gas stops. We then got a hotel, and I don't specifically remember but am nonetheless certain that both cats used the litter box when we put it in the hotel.

The next day was something like a 10 hour drive, and, again, I'm pretty sure we only let them out of the carriers at gas stops.

Nervous and unhappy cats can sometimes hold it pretty well, I guess. I know they both drank water at the gas stops, and I remember being pretty disturbed that they weren't urinating, but their voluntary hiatus from elimination doesn't appear to have left any lasting effects.

Dahmer wouldn't eat, drink or use the litterbox till it's a room/place anyways so in my case, I'd wait till I'm done driving for the night. Breaks will only make the trip longer.