Stopping sous vide to drive to relatives, then restarting

I've done something similar for Mother's Day, but my mom's place is a bit closer (35-45 minutes, depending on traffic, and I was cooking chuck steaks at 131°F).

In your case, you're actually out of the 'danger zone' of 40-140°F, and it's typically okay to leave stuff out on a buffet for 2 hours, so there isn't that much of a problem. And it's even less of a problem, as you've actually pasteurized the meat** before transporting it.

What I did for transporting is remove the immersion circulator, and put a tight-fitting lid on the water bath, and then transport the whole thing, slipping it in a cardboard box lined with bath towels (and then folding them over the top to close it in). Of course, in my case, I sort of planned for that sort of use -- I specifically got two lids for the vessel that I use, and cut one so that the circulator can slide in. (it was actually so I could use it for food prep/storage if needed)

As for the tasting okay ... I don't think it'll significantly affect anything vs. having cooked it in one pass ... but taste is a pretty subjective thing. (eg, if you added cilantro, then it will never taste okay, because it has cilantro). There are also some other considerations for flavor when cooking sous vide

** Look at the 'table' links in the linked question for pasteurization times.

I think it's fine to transport, and not even worry about the temperature or time. Kept in a sealed bag, your ribs have already been pasteurized and new microbes cannot enter.

This is similar to confit, which was common prior to widespread refrigeration. Quoting Wikipedia, "After...cooking in the fat, sealed and stored in a cool, dark place, confit can last for several months or years." In fact, "The word comes from the French verb confire (to preserve)..."

With sous vide, the ribs are "submerged" in a bag. No need to worry about the safe zone or temperature until the bag is opened, after which the clock starts ticking.

US FDA Guidance is that food should not be held in the "danger zone" (40F-140F) for more than four hours. Your ribs will have been well-pasteurized ahead of your drive. You are transporting them in a bag which will help the food to retain heat, and your interval outside of a cooking environment is going to be relatively short. Based on the conditions you set forth, I do not see any reason to believe you are compromising the safety of your food.

I see two options to pull this off:

1. Cool the ribs down really fast and keep them refrigerated throughout the drive (insulated bag/box and colling/ice packs). The downside is, that it messes with your cooking time and and cannot give you an answer on how long this will increase your cooking time.

2. Keep the ribs as close to your cooking temperature as you can by putting them in an insulated container and add some heat-source like some hot-water-bags or heat-packs. Make sure you don't have direct contact between heat-source and ribs (some towels will do). If available put a temperature probe inside the container (readable from the outside), near the bag with the ribs. As sous-vide is tolerant to additional cooking time, your approach on ignoring the travel time is okay. If you like, measure the temperature when unpacking and guess how much of the travel time will count as cooking time.

While i share @joes general view on pasteurization i would feel better if the meat would stay out of the danger zone as long as possible.

As i see no practical way to cool the ribs down really fast at home, i would strongly advise to take the second approach.