Can it go on an incline? What would be recommended to go under the turf in an outdoor dog pen that was grass?

You can install our Pet Turf Rolls on an incline. You would just follow the installation instructions that we have on the product page under the installation tab. You wouldn't need to put anything under our Pet Turf in a dog pen, but you can add our Zeolite Max to help mitigate odors and pet urine. This product you can place under your turf and in the turf as an infill. If you wanted to use our Durafill infill, you could always use Pet Fresh to help mitigate any smells. You would just spray it as needed per the instructions on the bottle.