For one horse, the free fed round bale would go bad by the time the horse got half-way through it. And I find free feeding round bales can waste so much hay if you don't have one of the metal things that go around them. I have 3 horses and they wasted so much by pooping and peeing in the hay.
I'd suggest building a shed or something for feed storage. It doesn't have to be large, but it'd be extremely helpful to have. You could try free-feeding for awhile until you get something built but I can just imagine the money going down the drain.
Covering hay stacked on pallets with tarps doesn't work well either. Our 3rd year of having horses, we lost 900 bales because we couldn't fit them in the barn. We had 11 horses at the time so we needed the hay, but there went over $2000 worth of hay. And cleaning it up was a mess too.
Live and learn though.