Almost always I drop my bike at the paddle take-out, (I paddle a SUP) then put in upstream and paddle down, bike back, drive home and pick up my paddle stuff on the way** Being in Stl it works well because the rivers run toward me and they often have trails alongside them. Missouri Meramec Mississippi.
I've hacked out workable routes in the Ozarks - Current River , Big Piney, and upper Meramec using backroads and trail.
up and back paddling is OK certain times of year.
I do use car shuttles with friend -for MR340 my friend ran his van and trailer upriver - all masked up, windows down, little conversation in the vehicle. Gawd, it will be so great ahead having more shuttle options.
**as you probably know, river accesses and trailheads are notorious for theft. So far I've had no issue with theft vandalism. - I can put a half-ass lock on my SUP, but ideally I lock and stash it and my paddle in the weeds. My bike cost 35 dollars 20 years ago but I lock it up. a few times I had trouble finding where I hid it all lol. I tend to go off-peak time - like tomorrow. But frankly, having my vehicle window smashed open is probably what is most likely to happen.