I finally gave in, and bought a Pro-Fit antenna mount (Pro-Fit TYANTPF, see here
Antenna Mounts for Trucks and SUV's, NMO Mounts and Fender Mounts), and a Larsen NMO coax cable, and a Larsen NMO27C antenna (for CB). Bought all from The Antenna Farm. I'd give it a 4 out of 5 stars. The following are my notes/thoughts:
-Mount is meant for left side only. If you put it on the right side of the truck it would angle the antenna forward. So it's left fender only. [Maybe some day I'll try mounting on the right side to see how bad it's angled.]
-It's not a stiff as I'd care for. OTOH they couldn't make it any thicker, or it would not fit between hood and fender.
-One of the mounts that is screwed into the fender (a generic mount) is probably more stiff, despite being of the same gauge sheetmetal, simply because of less metal that can flex.
-it's not 100% fitted. I spent a few minutes with pliers, bending it just so. Which means it's a good thing it's not thicker metal. I would not let this deter anyone, as it was just a few minutes with pliers to get it to where I was happy.
-There are some sharp edges. I forgot to file them down. Shouldn't matter, as the mount should not hit paint. Except the bracket feels a bit flimsy...
-I put a wrap of electrical tape around mine, in case of contact to the fender or hood.
-My first thought is that this Larsen NMO27C antenna (for CB) is too much antenna, as I could easily make the mount flex "lots" in the driveway. But on the highway today the base barely moved around, so perhaps it is stiff enough. This antenna is about the same size as a 2m 5/8's whip; but I'd be hesitant with any antenna with the loading coil(s) located up higher.
-Larsen's directions for trimming the NMO27C was about spot-on, 47-ish inches for fender mount. Can't comment on range/performance, as I plan to just monitor CH19 for road conditions, or use a 2m antenna for local work.
-Not sure what coax it used, but it's about the size of RG58. Which is the most you could get between hood and fender. As it is I'm a bit concerned about paint rub.
-I think I'd buy another one again, assuming no rust issues or stupid stuff like that.