Cardboard covered with pine shavings (or cedar shavings ONLY if there will be no livestock there) works, too.
Everything breaks down eventually. If thick, it will be harder for the weeds, but there is NO forever substance, bc even cement and ashphalt get cracks for weeds to grow in.
I have used GroundClear to kill weeds, then cardboard, then some kind of mulch and that works FOR A SEASON.
I don't think that you have the amount of acreage that I do--weed clearing/mowing on 5 acres. You can handle it, if you make the work into bite sized pieces to handle.