I've driven full-size broncos for the last 13 yrs, though usually not on long distance trips. One or two dogs is easy -- varikennels. But I have no use for the rear seat. With that out, my dog box slides right in.
I guess when you show your hounds, you get in the habit of bathing them pretty often.
We have a lot of poison oak around here, so we usually bathe after hunting anyhow since the dogs are nearly always out in the yard where they're in constant contact with any human who comes on the property.
I don't know if the Jeeps are narrower across the back than other SUVs, but my box was originally custom built for a Jeep J-10 pickup, so that may be why it fits in my broncos just fine.