here is one that i found:
Firestik SS204A Adjustable, SS Vertical Door Jamb Mount
it says in the ad that it is not for antennas over 4 feet in length.
i was already thinking that the 108" whip would be too much for it, and the ad/ picture confirmed it.
the 108" whip will beat that mount to sh!t over time.
it sounds to me like you are ok with drilling some holes in the vehicle, but is there a reason you are hesitant to drill a hole in the center of the roof and maybe mount a wilson 5000 up there?
remember that with the wilson antennas, the antenna and its base will unscrew, and a little black plastic cap that is included goes over the connector on the roof.
with the antenna off, you can barely tell there is anything up there.
if you sell the car, you can just leave it there and buy just a new mount.
anyway, if you are dead set on this mount, i would go with the wilson trucker antenna, or the silver load you mentioned.
the 108" antenna should only be put on the mount when you are stationary.
ideally, the base of the antenna should be level with the top of the vehicle, so try to get as close to this as you can.
also, you are going to have to run the coax into the vehicle somehow, and repeatedly slamming a door on your coax is not going to be good for it.
coax works on the principle that the shield braid is a certain distance axially from the center conductor.
when coax gets smashed into funny shapes by car doors, that relationship can change, causing your coax to not be 50 ohms anymore.
dont fool yourself into thinking that the door will never get slammed on the coax, it will happen.
if you are going with the door jamb mount, you need to pay special attention to how you drill the holes for the screws that will hold it to the vehicle.
how you do this will determine the strength and security of your mount.
first decide what size hardware you will be using. i would think that #10 or #12 hardware could be used, but if not, #8 should work.
this is the screw you want to use (this is #10, but again, use the size you feel you need to)
#10 x 3/4 in. Stainless Steel Pan-Head Phillips Drive Sheet Metal Screw (25-Pieces)-34552 at The Home Depot
you definitely want stainless steel.
here is a chart that will tell you what size hole to drill in the vehicle for the screws:
Pilot Hole Drill Sizes for Starting Sheet Metal Screws
use the right size drill bit, as the size of that hole determines the purchase of the screw to the vehicle.
when you go to actually screw the screws into the vehicle, make sure to set your drill oh slow speed, and set the drag so that you wont strip the head off the screw when it gets tight.
they will snap the heads off if you dont drill the right size or try to power the screw past the point of "tightness".
you might be fine with 1/2" long screws, but unless you think there is a clearance issue, i would go with the 3/4" screws.
do the install like this to make sure you get a chance to level the mount before committing to a hole location.
1. hold the mount where you want it and mark one of the top holes with a sharpie.
2. remove the mount and drill the correct size pilot hole for that screw.
3. put the mount back in place and VERY SLOWLY screw the first screw in JUST to the point where it snugs the mount up enough so that it will stay where you move it to.
(DO NOT screw the screw past this point, as sheet metal screws NEVER get as tight the second time they are screwed into the same hole. its all about getting it right the first time)
4. using whatever means you have available, make sure the mount is level so that your antenna wont be sticking up at an angle when you are all done.
5. when the mount is where you want it, mark the other three holes with the sharpie, and then using the right size pilot hole bit, drill them just enough to create a small divot in the metal. do this to all three holes that are left.
6. now, with the mount still in place, drill one more pilot hole. just one more for now. (i like to choose the hole directly off at an angle from the first hole)
7. screw the next screw into this pilot hole, BUT AGAIN GO SLOW!
this time you want to stop just short of snug.
8. check the mount again for level, and fully tighten the screw you just added. (remember to set the drag!)
9. fully tighten the first screw.
10. check the mount again to make sure you are happy with it.
now you see the reason we did it this way.
if you need to adjust the angle of the mount, you can slightly loosen the first two screws, adjust the mount, and you still have two "first time" screws to add for strength.
11. if you are happy with the angle of the mount, drill the other two pilot holes, and screw those screws in.
you should have ended up with a very secure mount doing it this way.
good luck,
LC