look for a national forest river
I don’t know much about the rivers out west other than a few famous ones, but I think what you want for a trip like this is a remote wilderness river well away from civilization. I doubt the Sacramento fits that bill, but I wonder if you might not have a few good candidates within a day’s drive to the east or northeast.
If your group has done a couple of extended hiking/camping trips, then I’m guessing you all are pretty expert when it comes to camping skills. It strikes me that a group like that might not be very happy in KOA campground off a highway near the Sacramento. Wouldn’t it be more fun/instructive/challenging to do primitive camping with a “low impact/leave no trace” ethos in a wilderness area? To me, one major part of camping skill is knowing how to select a campsite from the wild and deciding just when and where to stop a day’s travel to camp. This also frees you from rigid daily schedules of having to reach the next public, pre-reserved camping site, so you can spend more or less time at points of interest along the way, as they deserve.
Nationally, most designated National Forests allow primitive camping anywhere in their borders that is not otherwise designated. Rules may differ in the West and especially in California, so I recommend you check local regulations. Looking at an index of NFs, I see a couple dozen that appear to be within a day’s drive of you. Thus, I think your ideal trip would be to an obscure river in one of these NFs that allows primitive camping.
Also, I second those who have suggested you should use mostly tandem canoes. I’m not sure, but in some parts you sound like you are determined to use kayaks, but I’m not sure what the reasoning is. Canoes are easier to use, carry more gear, are easier to find for rental, are more forgiving and more flexible. Using mostly tandems allows you to pair up paddlers based on skill levels – for example, putting a weak paddler with a strong one for the former’s protection, or putting two very strong paddlers together for use as extra-duty scouts/messengers/foragers. For variety, you might take along one or two kayaks to let the boys try them out at different times, but I think most of your fleet should be tandem canoes.
Bay sojourn
I’m not sure the OP is ready for the SF Bay sojourn yet.
I remember I tried the SF Bay Sojourn at the end of my first season and found it quite challening, even though I came from WW background and can handle the water. Making speedy progress when it’s blowing 15 knots and white caps isn’t something to be taken for granted. So many of BSK’ers are accomplished rough water boater, sometimes unsuspecting beginers got sucked into trips over their head.
Bo is a very nice guy. But his style of paddling is more along the line of “Small Crast Advisory? It’ll be a fun day”! I’ve gotten used to SCA now but it was pretty intimidating for a first year paddler, which the OP is.