There are slide in multi hole boxes, I have a 3 hole with top storage. I am 6-3 and the top storage is hard to reach but I can slide the box in and out with no help in 60 seconds. I use(d) this when I was working and I would be assigned different trucks from work.
I have a cap with sliding, screened Windoors on each side. Built a 2 drawer vault and any number of foldable wire crates. There are many sizes, width is really the key dimension. I found some 20 inches wide, tall enough and long enough for 2 setters in each (I usually only double in one crate. You can reach in the Windoor and get to all dog doors. For cold weather I cover and use binder clips to hold in place, with wool blankets. A better idea would be those quilted U Haul blakets, or, if the budget allows, buy fabricated insulated kennel covers. Blankets are cheaper. I hanng heavy towels oover the door to complete the cover. There is always warmth eminating from the box when I let them out in the AM. It's hokey, but it works and the cost was very low.
I found this to be the best setup for me.
If I had 2 more dogs I would get a sit on the bed rails dog box. This will provide all the room needed underneath for storage and separate boxes, one for each dog. IF YOU do this make certain the width of the box fits on TOP of the bedrails fits well and the bottom plate IS NOT cantilevered inside the bed. I watched a brand new box, designed and built this way, collapse on the truck and fall into the bed. The cantilevered plate bent and the welds broke in a few spots. The owner was lucky he was a trial where 8 of us could get it out of the bed, jury rig it for travel back to the fabricator.+