Where are you going and how far is it?
One of the places I go is a lake 16 miles from home, at 8 MPG it costs me $10-15 for fuel (counting the trip to RV storage and back). I spend $8 a night for the campsite.
Another place is a city park 40 miles away, $5 a night for the parking spot with hookups, $25 to $30 for fuel.
A favorite place on Grand Lake is 80 miles way, $30 a night, $50 to $60 for fuel.
Most distant place we would regularly go is a golf resort 160 miles away, $35 a night (plus greens fees) and $100 to $120 for gas.
Those are the place I choose to go. I've had nightly site fees as low as $0 (one night or two nights free in a city park) and as high as $150 at family resorts at major destinations like Disney World, or near big cities like NYC. Commercial parks catering to families might be $30-$80 a night in less popular places, and I've paid $16 to $35 a night to use state parks.
Food costs what food costs, whether camping or at home. I get by on $120 a week for groceries, for myself. When my wife was alive, it was about $180 a week for groceries, and taking her out to eat at least one meal five days on the average, so another $120 to $150 dollars at the cheap local restaurants we visited (big chain places, bar food, or fancy locals can cost a lot more).
Activities? We generally didn't buy any, but you might look into cost of things like boat rentals, amusement park fees, and so on. I've been to family resort campgrounds, and while some had separate amusement park or activity fees per person, others added it to the campsite price whether you used it or not.