Another option you can do on Pick-ups is mount the antenna on a riser off your bed rail...(This riser is made from a ceiling fan drop-pole from Home Depot, and a mirror mount)
Mounting like this, you still get the same effect as if the 10K was mounted on the roof! Just be sure to ground whatever you use as a Riser good.
The Single Coil Predators IMO are still the best of the bunch, and I have just about every configuration of Predators ever made lying around in my shed.
The Mag Mounts will hold any of the Predators at 100 mph, but like mackmobile43 was saying, I don't recommend putting a 10K on the roof with any shaft over 17" long...
The taller shafts just manage to find everything there is to hit too easily and will snap off at the base when the antenna hits something solid...
I have two of these 27" broken shafts now!
You "can" use a Barrel Spring (like used with the 102" Whips) on a Single Coil 10K with a 12" or shorter shaft if you want, and they work fine...
The antenna will tune as if it had a 17" shaft. I know several guys around here that have theirs done that way, and no problems.
Just don't use a spring on any shaft longer than 12" tho...otherwise if you do, the wind drag from the Coil will cause the thing to dance around on the roof!
By the way..."Where do you guys live, where you can drive 100+ MPH all the time?" Around here...If you get over 69 MPH, your A$$ is Grass!