The box I use the most is 17" tall and was built to that height so my collapsible shovel handle and come-a-long would fit inside, the handle fits diagonally. This box is the same size as the rack. The first box I built was 23 inches tall and stepped up and out over the side racks and tail light but it was to big. It held to much junk and was to heavy.

 

The box I use the most is 17" tall and was built to that height so my collapsible shovel handle and come-a-long would fit inside, the handle fits diagonally. This box is the same size as the rack. The first box I built was 23 inches tall and stepped up and out over the side racks and tail light but it was to big. It held to much junk and was to heavy.

Mines 16", good point is to build your box around the things you plan to carry, to high makes the sled more top heavy, no mor height then you need,

 

Mine is 18" high (It's 18x18x18) I could go a little higher and not look too funny but that's how it came.

(It's a Jobox underbody truck box).

 

One other comment - No sure if you use them, but if you plan on carrying extra fuel, making the sides big enough for Rotopax is a good idea.

 

Mines 16", good point is to build your box around the things you plan to carry, to high makes the sled more top heavy, no mor height then you need,

That's why I went with an open top. I didn't really know what I wanted to carry.

 

My cargo box is about 28" high. I believe Mik Mac also fabricated it.

 

I am in the process of welding one up out of aluminum that will be about 2' tall when done. I'm about 1/2 done but I got stalled out with a new puppy so welding is out for a little bit until I can get puppy trained to stay away when I'm working and not chew on things in the shop.