I just installed a set of three way dynaudios in the doors of my 2009 Colorado. I think it is a very similar chassis. I originally wanted to use the a pillar, but there wasn't much room there to work with, both width and depth. I ended up putting them on the top/forward of the door panel, which took a little metal cutting(but not too much) to get them to sit flush. The colorado has a plainer? Panel to work with than yours, just a pretty much flat surface. I'm not happy with how far back towards me the soundstage is, though. And I'm running active without a dsp, so dialing them in is taking a lot of time. Still not there yet.
The dynaudio tweets seem to have a very wide dispersion to me, like they are pointed right at me, no matter where I'm at.
Since I've cut up my doors, I wonder if I should have mounted them in the corners of the dash reflecting off the windshield, to bring the image forward.
But, i think the a pillar pod for the three way would be pretty huge in the truck, let alone just that big tweeter. In the Ram it might not be in the way, but the H3 doesn't have as much real estate to work with.