I'm still wondering why you need a truck to move pins. I own a truck and wouldn't let a single one of my pinballs touch the bed of that damn thing. Who wants their new game exposed to the elements, sunlight, rain, heat etc. Sure you can slide by if you're going short distances on a perfect day but I would never drive across state lines to buy a game only to toss it in the back of my truck open to the weather.
I would suggest getting a full size 4x4 SUV. It has more than enough room to carry one or two single games covered as well as the hp\tq pulling a trailer etc. I guess you could put a camper on a truck and accomplish the same thing... but I would personally go with a SUV for moving pinballs. If you don't mind having the games exposed to the weather I guess a truck without a cover is the way to go.