Yeah, I have been meaning to look into my options for this as well. My '99 F-150 that I sold had a nice grab handle on the passenger side that hung down below the A pillar. If I could find one of these, I could probably figure out a way to fasten it to the passenger side A pillar. Here is a picture of a similar one.
Not sure what to do in the back seat though, maybe these would work above the door too, I don't know. I need to just go peruse around the junkyard a while... I am sure something will come to me.