Lol, I used to let my birds free range COMPLETLY, I live way out in the woods too,i lost birds because my chickens would go 100's of yards into the woods and get killed by daytime predators.sometimes coyotes,bobcats,dogs,hawks....
I dont do that anymore,i couldnt see losing my hens to predators like that...
I bought ALOT of 4 foot chicken wire,and made me a 80yardx50yard chicken area. I still consider that free ranging.I dont know about 40' by 50' kinda small,but i bet it would still be considered free range because they have access to fresh vegatation,and bugs and worms and natural chicken food,instead of only getting commercial feed.As long as you didnt have 30+ chickens on 40'x50'.. But i can see 8-12 or so on that.