Depends on your lifestyle choices, where you choose to go, types of places you choose to stay, how much you move per day.
I find the cost of moving is 40 to 50 cents a mile for the RV I own, and as it has aged, cost of ownership has slipped from abiut $8000 per year to $4000, but if my RV were 10x as valuable, ownership costs would rise proportionately.
On the average, when traveling, I pay $30 a day for my parking site, $10 per day per person for food. But those costs can vary greatly, because parking at popular tourist destinations, or near metropolitan areas may often exceed $50 a day, $150-200 at the top RV resorts in peak seasons or for special events; at the other end of the scale, the site cost can be zero on public lands and some municipal campgrounds, up to $20-25 in developed public camprounds, sometimes more at beaches. I most often pay $8 a night to camp at a lake on the Arkansas River system.
Similarly, it is pretty easy to push food costs over $50 per perso per day, if you want to eat out and eat well. Some resorts, and better restaurants, may be on the order of $50 per meal, but that cost and quality level can be hard to find outside major urban areas.
So costs are about choices. When trying to cover ground, 600 miles a day, I'll be spending $300 a day on fuel, for family of six about $120 for low cost restaurant meals, $35 for a campsite. To keep up that pace indefinitely, upwards of $3000 per week. Slow that pace to 200 miles a day with sightseeing, it is $100 for fuel, $35 for campsite, $30 groceries, maybe $30 admission fees (although that can go much higher at major destinations like theme parks) for about $1400 a week.
When I'm just camping, it is about $30-50 mileage cost for round trip to a lakeside campground, about $100-150 worth of groceries, $56 for the campsite for the week, $200-320 per week overall.
How much of the U.S. do you want to see in a year? It is pretty easy to run 15,000 to 20,000 miles and not see everything (that barely covers a loop around the perimeter and one trip across the middle. That's about $10,000 in travel costs, maybe $1500 a week living costs. A maximum pace, might be able to cover 150,000 miles in a year, not a lot of time sightseeing but you coul cover most of the country, 75,000 travel costs pushing total weekly cost to about $4500.