the pillar idea sounds good to me. I absolutely hate to drill into a new vehicle- inside or out!
Any installs I have done in the past years have nearly all been "no-drill".
The radio itself is under the drivers seat. I sealed off the heat duct with aluminum duct tape (real metal duct tape, not the fix-all stuff) and to keep the radio from sliding I popped a piece of velcro on the bottom. Used the harder loop side of the velcro.

For a mic hangar I used one of the command adhesive hooks from 3m. Radio head mount was done with a special swivel bracket I picked up at HRO.

This H3 is actually the first vehicle I have been able to NOT install a line filter on. I have had no alternator whine or ground loops at all....

I can post a pic if you want to peek sometime.