How do you safely travel with guinea pigs?
I traveled across country with my three guinea pigs and back home. At the time, I had a large wooden box that I had for their regular home. They traveled well and even seemed to like the experience. They had plenty of room and their regular food and water dishes. IMO, a large carrier with their regular bedding, hay, straw, paper, whatever, their food and water dishes and hide box and you and your piggies should be just fine. Just for your important information, California does stop every car and asks if you have any fresh produce or plants, so, before getting to the check point, dispose of any produce you still have for the guinea pigs or yourself and buy new stuff once you're in California.
Get them a big travel cage and put in the travel cage some stuff they had at there cage like a toy or something that smells of home this will carm them and help the settle in you new home
I suggest either asking a vet or at least look on the petmd website
They can stay confined during the day and be okay for a few days, at night though we used s big cardboard boc so they could run around and get in some exerceise, always breaking their night home down in the morning. Make sure you use good strong packing tape and a towel so they cannot jump out of the box, or a sheet so they can’t jump,out.
How can a car ride be better for them.... 5 days of stress vs 7 hours of stress... You probably don't have any choice but to move them via the car, but that doesn't make it a better option for them.