Here is a dog box to fit a Rhino. I built it for lion hunting and it worked great. It hauls 4 dogs fine and has a piece of carpet I tied on top so I could use it to rig a dog on top. It has no floor to reduce weight and has turn buckles to hold it in. Its a welded steel frame with aluminum riveted to it and 6" strike holes. The only problem I had with it was the dogs got hot in the summer (after 2-3 hrs of bear hunting) so I built a bigger box with removable pannels for summertime.
The dimensions are 36" wide, 22" tall (plus a 5" high rail around the top), and 30" deep. I think it weighs about 75lbs.
I'm not sure if it will fit other machines but anything can be made to fit.
I would like to have $200 for it or pos. trade for something....NOT DOGS