I have a 32' x 32' square pen for my pigs. They have a 3 sided shelter with the 4th side half covered and straw bedding. There's a 55gal water barrel and a creep feeder that holds slightly over 50lbs of pig food.
What you're suggesting is the equivalent of stuffing a dog into a crate for 4 months.
Pigs are living, breathing ANIMALS. They need proper food, water AND housing. They like to dig in the dirt, wallow in a mud puddle, have their butts scratched and their tummies rubbed.
And YES it most certainly matters if the pig is able to walk around and exercise! It would be like stuffing a horse in a 10x10 stall and leaving it there for 4 months. Downright cruelty!
It's very simple, go to the nearest farm and ranch supply store and buy a few t-posts and a minimum of 4 hog panels. Put the t-posts at the corners and wire the panels to them. Then take the 2x4's and plywood you have and build the pig a shelter. Pigs BURN if they do not have shade.