Jim, i would suggest seeing if their is any support or even captured nuts behind the headliner in the sheetmetal of the roof structure... then you can figure out where you need to put holes to run the screws through. no reason you couldnt use a pass side handle if there is support for it.
Not to be an asshole but just use the steering wheel. I've wrenched my back a few times and needed to use the wheel to get in and out of the SS a few times. I looked in the sheet metal above the door for the same reason and didn't see it worth it to cut holes in the metal or the plastic. If you do come up with something that looks good and doesn't fuck up too much of the truck let me know.
I'm assuming that your wanting to add this grab handle just for getting in and out of your SS, but my first thought was. If I'm sitting in the passenger seat and the guy driving dives off into a corner hard enough that I grab the handle on my side.
Then the very last thing I want to see, is the guy whose suppose to have both of his hands on the wheel, turning loose of the wheel and reaching up for that grab handle thingie. Then my next thought would be, "O LORD, I know that Jesus has prepared a mansion for me and I'll be there in just the twinkle of an eye to take possession of it!" Thank you Jesus!