Take a different approach. Near cities and attractions are where the 'weekend' crowd in prime season whelmes camps.
Adjust your plans to off prime visits in even the most desirable locations prime sites in desirable locations will be available at discounted rates on short notice.
Find new developing private camps where the 'word' hasnt gotten out yet, Might not be much for facilities, grass young, construction of amenity ongoing but it will be welcoming $ reasonable and spacious. 6 rigs in an 60 site section. Mgmt gave us 2 sites for our mc trailer and truck parking. Told him I d water the grass both sites.
We are in one like that now in Bandera, prime Tx hill country. have been using new camps for years in prime places and times.