blackjack covers

Can I add a sliding door to my lean to?
I am looking at rescuing a horse and one of the requirements is to have a 3 sided shelter. Well the barn is full but the lean to isn’t. It has 2 completely covered sides and 1 side with a fence. On the other side of it, can I add a sliding door to it so that it is 3 sides?
http://s232.photobucket.com/albums/ee172/blackjack3296/?action=view¤t=barn2.jpg
http://s232.photobucket.com/albums/ee172/blackjack3296/?action=view¤t=barn.jpg
http://s232.photobucket.com/albums/ee172/blackjack3296/?action=view¤t=barn3.jpg
http://s232.photobucket.com/albums/ee172/blackjack3296/?action=view¤t=barn4.jpg
Sorry if on the last picture it’s a little hard to see it… BlackJack wanted to be in the picture too:)
Thanks ahead of time:)
yeah you could add a sliding door but i would just build another wall so that all 3 sides were covered permanently
Black Jack cover – Kedada Mallorkin en Rustic