If they do mak a mess in their kennels, they clean it up themselves! hahaha!! Brades actually has his on a carpeted floor and seems to be ok with that....but he doesn't drool over it like she does (plus, it's carpeting thats getting torn up so I dont' pay attention much...once new carpeting is in there, I will figure something out).
Also, specially for dogs like Beckham who are alone for longer stretches, they make a machine that automatically deposits kongs every couple hours. It fits 4 kongs, and I think you just set the timer on it. If we didn't have the dog walker come each afternoon while we were at work, I would get one of these for each dog. I think they are about $120, but money well spent to keep them entertained. Fill with kibble, pumpkin or peanut butter, pop in the machine and apparently it beeps right before it drops one out, so the dog hears the beep and gets all excited! I think it's a great idea!