If you only had 2 rubber stable mats would you put them at doorway or back?

Not sure what you mean when you say the rubber mats would help soak up the pee? They won't soak up anything and that's the problem if you use just mats and no bedding on top of them. Urine can run between them and pool underneath and the pong of ammonia will strip your lung lining in no time! My horse has mats at the front 1/3rd of his stable. Deep litter shavings bed at the back 2/3rds and a strip of about a foot of both where they meet. This means horse is standing on rubber most of the time (front is where haynet is and where interesting things can be watched) and when he wants a pee or a lie down he goes to the deep litter 2/3rds. Works a treat. Have hardly touched deep litter bed in 5 years.
 
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