There are Encore parks in the area that get about $900/mo and $1,050 with 50 amp. We've found that Encore is high as a cat's back (like KOA) but usually clean and well maintained across the country.
Charge what the market will bear is sort of the world's mantra. Mom and pop RV parks are going the way of the mom and pop farms. Oh, did I mention the mom and pop grocery stores, hardware stores....
In our travels around the country we see that the small, private resorts/RV parks that families flocked to back in the day are quickly deteriorating, folding, being left to be used for other things. Young people are generally not willing to work a dairy farm milking 40 head of Holsteins, working 20 hours a day, 8 days a week. The 'farm' down the road is milking 5,000 head of cows, three times a day, with two milking carousels and 40 employees.
The day of the $20/night RV parks are about over. And 30 amps? Even 32' RV's are sometimes equipped with 50 amps. Try to camp in hill country, Austin, Texas area for the month of July with 30 amps and 32' of RV. 50 amp service is almost mandatory these days and old RV parks with 30amp aluminum wiring built in the 60's aren't going to survive.
If you are going to attract a crowd of campers you will have to have good amenities and what you charge will be secondary.
I guess all the mom and pop RV operators are working 40 hours a week? Uh huh, dream on.