I bought a 4x8' Chicken Coop, but am building an enclosure for them. it's going to be around the side and back of the coop. I had some old/used preasure treated 4x4s around that I'm using as a base around the perimeter, burying chicken wire under it. To build the sides, I was planning on using untreated 2x4s, staining them to match the coop. However, I was wondering if I could use 2x3s instead. The sides will be 5-6 feet, one side with a people door. I can afford 2x4s, but am a cheapskate, so thought I may get by with 2x3s, what do you think?