A tent footprint’s only job is to be durable and packable. You want tough material for your footprint, especially if you’ll be using it in more rugged terrain. Higher denier material will correspond to more sturdiness and durability. Since you aren’t concerned about comfort with a footprint, it’s best to prioritize durability.
A footprint should be a bit smaller than the actual square footage of the bottom of your tent—up to 2” smaller. If your footprint is larger than the tent itself, you run the risk of water pooling around the floor of your tent. With a smaller footprint, you avoid this issue.