IBcarguy,
Our experience over the last 52 years is that the West Coast states (mainly California) has this vast problem so much more than the rest of the USA or Canada. Coastal CG's are always popular and California is no exception. California has far fewer CG sites per capita of the population having RV's or even tents than anyother region we've seen. California, for instance, is very seriously lacking!
We generally only use CG's in the Midwest and the S.E. and Canada now because of this nagging and PIA West Coast issue. Besides, been out west, NW, and SW dozens of times and have grown very tired of it and the plains states too.
Michigan, the state weve lived in for 75 years now, and it has over 3200 miles of Great Lakes Shoreline alone and more than 11,000 inland lakes. Michigan has a total of nearly 4,000 CG's having around 363,000 total campsites and you can usually always find a site without even having any reservations except for many of those directly on the West Michigan Lake Michigan Shoreline which is extremely popular, of course, during the summer months and much of the Fall. Florida also has an awful lot of CG's to choose from but you sure don't want to be there in the summer months or Fall. We have never had a problem finding a site without reservations in Florida in the winter either for 2 to 2-1/2 months of total stay and is where we are right now in a wonderful CG and NOPE, didn't have reservations here either and it's still winter.
Really, just what's needed is a lot of CG directories/books like: state published private CG books/literature etc, Highways/Good Sam RV book etc, COE CG locations books (Corp Of Engineers), BLM (Bureau Of Land Management), Passport America 50% Discount CG books (need to join but is cheap), ALL of the U.S. State Parks in the USA book which also lists CG's, etc. So many more and much of the info is on the Internet also. All sources will have the phone numbers in them so you can call with your cell before going to them when on the road and many will old the site for you if close. Some require a min payment obligation or vehicle license number and description of rig but not many do. Some states allow the recording of your phone call for agreeing to use the site at the fee and some don't allow recording. You are calling them and requesting, not them calling you and asking you to come in and stay!
Only been RV'ing a lot for 52 years now and have only gotten any reservations anywhere less than a dozen times in all those years and have never gone without a site once. Have had to go to or call 2 or even 3 CG's a couple times for an open site but always got a decent site in the area we wanted to be at. A planned daily life is NOT for us!
Your problem is a local state problem where you live and virtually not in other areas of the country normally. Yes, IF there's a very large local event going on like a fair or a popular festival, or college game day, etc, most CG will be booked but you learn to avoid these areas at that time unless you want to be at the venue. Then, you usually must have reservations early.
Are you always going to get the exact site in a particular CG that you want? Nope! You are only renting the site for a short time (day or week, etc) Not owning it or buying it so you are just a number like everyone else. Be flexible and suddenly you will be winning more than adequately! You can't take a particular CG or site with you! Just pay to use it!