I think it will work out ok for you. We went on a road trip with my parents in 2004 and our 7 day vacation turned into 21 days. LOL. (My dad had a hospital stay). We stayed with family for a small part of it, but the rest was car travel and hotels.
We had a large cooler in the hatchback and when we were hungry we'd just pull over to a picnic area (if available) or eat in the car. We kept things like deli meats, yogurts/gogurts, string cheese, block cheese, ketchup, mayo, mustard, milk, water (that we refilled at our hotels at night) and occasionally soda or juice. We even had macaroni salad and potato salad sometimes. Oh, and pudding and jello packs were in there too.
In a large tote next to the cooler we kept crackers, chips, cookies, cereal, bread, and a few snacks like fiddle faddle, combos or goldfish, etc. We also kept plates, bowls, napkins, wet wipes, and silverware in there.
We ate most of our suppers in restaurants or with family. We averaged one meal per day in a restaurant or with family.
We took advantage of the ice machines at hotels and filled our cooler with ice each morning before leaving for the day. We only bought ice once or twice during our entire trip.
We also took advantage of the free continental breakfasts offered at the hotels.
We at a lot of sandwiches but it was a lot cheaper than hitting fast food everytime we were hungry.
