I've driven across the country (CT to ID) seven times since I had my surgery. At home, I use a bidet to manage issues south of the border, and it works great. On the trip, so such luck -- not many hotels have bidets, right?
While I did have a travel bidet/peri-wash bottle, it was nowhere near as effective as my real bidet, which actually gives me an enema when I need it to. I quickly learned that I had to manage myself through diet if I was going to make it through the trip. I stayed on a mostly liquid diet during the day, with yogurt or an Ensure for breakfast and lunch. I still needed to hit the bathroom from time to time, but it wasn't that bad. Dinner was my one "real" meal of the day, and I usually got rid of that either during the night or in the morning before pushing off for the next leg of the trip.
I will say that the accumulated irritation got pretty bad by the time the trip was over (about 4-5 days usually). Getting back to a proper bidet was a nearly religious experience. But during the trips I had no really scary urgency issues or "gotta pull over right NOW!" moments. The liquid diet seemed to be the key for me.
Enjoy the trip! I'm planning on taking my wife to Alaska for our 25th anniversary next year. We'll be doing a road trip, towing our camper -- the one with the bidet 