OP,
I have a very similar setup. I have 10 acres, 7 of it wooded. The front 3 are cleared (former farm ground that's been graded and seeded 7-8 years ago). I cut a 50 yard lane, into the woods, which created a 150 yard range. The lane is just wide enough for my truck. The backstop is built from railroad ties placed horizontally in a U shape, about 7 feet high. I shoot into the open end of the U. A second, removable layer of railroad ties are placed vertically in the interior of the U, so I'm shooting into two layers of ties. When the vertical ties get too shot up, I replace them. Some calibers will penetrate into the U, but in 8 years of shooting, it's still very sound.
Lately, I've taken some of the "shot up" pieces, cut them in half where they were shot up, and stacked them horizontally in front of the vertical ties, creating a third layer. I've been using this for some of the "heavier stuff".
Having your own range is one of the nicest ways to enjoy shooting. I built mine shortly after I had a neighbor of a private club scream in my face when I was shooting FA. Why an idiot would square off and scream at someone holding a machine gun is beyond me, but that's what he did. I reconfirmed that FA was allowed at the next club meeting (I had already been through this, but felt like I should re-confirm, as well as make sure the club was aware the neighbor was upset). I finished my range as quick as I could, just to avoid the hassle.
BTW, dirt makes a much better backstop, but at the time I had no place to source it from for free. If we ever build out there, I'll replace my backstop with dirt from the basement.
Enjoy