Trip apps are constantly improving. I have used several different apps like Gas Buddy, ParkAdvisor, RV Trip Diary, AAA, RoadTrippers, KOA, Good Sam, Compendium, Host Camper, and a few others; but the best that I have found currently is RV Parky as it allows me to plan and budget, especially long trips, free, taking into account, mileage, fuel, stay duration, notes. I've used a written RV Trip log but that now seems redundant given the sophistication and ongoing app development.
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