I dont know what size your frame is, or how often you use the your truck for cargo, but I mounted a couple Yakima blockheads http://www.yakima.com/shop/bike/truck-bed/blockhead on the back of my back seats. When I fold the seats down I can haul the bikes inside.

I only use this system now when I am not going to be near my truck and bikes at any time or overnight storage when camping. The rest of the time I have a hitch mounted tray rack like you mentioned earlier.