When I left on my trip back in January gasoline prices were relatively low and by the time I returned 3.5 months later prices had risen substantially. From past experience I know not to buy gas in Connecticut and to limit buying gas in California. Connecticut is a relatively small state so I didn't have to buy gas there, but my travel route in California I wasn't so lucky.
I have been asked what the cheapest gas was and what the most expensive was. The cheapest was South Carolina at $2.98 in late January on my way to Florida. The most expensive was in California at $4.69 later in my trip.
Traveling back and forth to CA from AZ I would stop for fuel in AZ before crossing into CA and hold off buying gas until back in AZ. It can easily be $.50 per gallon difference.
After I got my Good Sam card I planned my fuel stops at Pilot and Flying-J truck stops. Truck stops are generally cheaper, so stopping at one of these sruch stops was a better deal.
In the San Diego, CA area I found gas at $4.17 when other stations were much higher.
I would use the Poynt Application to search for lower gas prices within a reasonable distance or by planning my route to allowing fill up at lower costs. I would have to make the decision on how much it would cost to save a few cents per gallon. In CA the difference could be large enough.
Most of my trip I bought and cooked my food in the camper. Food prices did not have large fluctuations but Arazona has the lower food costs.
Generally speaking campgrounds that have the word resort in its name are higher in cost than those that don't. I was not looking for resort locations but did try a couple. The problem is that campground pricing are not generally listed on the internet with the exception of state, county, and National Parks. This makes it hard to plan ahead unless you call and ask what their pricing was. In FL I was tired and called and their pricing was over $40.00 and when I got there I negotiated a lower price to stay in an overflow area. Most campers are not like me staying just a day and they are seasonals or weekly to get better rates. Camping costs need planning.
I used the application AllStays to locate campgrounds, casinos, and truck stops to stay at.
As expected, gasoline is the largest variable of the trip followed by campgrounds.
AllStays gives costs using $ signs for each location. This gives you an idea on costs but the key was seldom accurate. It is best to call ahead. During the winter in southern FL and AZ many state and federal campgrounds are booked way in advance and my leave you going to more expensive private campgrounds.
What many places do not tell you is that if they are full they may have overflow available, so if the website shows full call to see if they have overflow. I did this in Havesu City, AZ and Mesa, AZ State Parks and got in at a lower rate I just didn't have hookups. Since I didn't need hookups it worked for me and I didn't mind paying less.