Transportable shooting backstop

[SuperMagnum]

Anyone ever made one? I'm thinking about making a shooting backstop so I don't have to drive 20 miles just to shoot my rifle at 100 yards. I have open fields but not many hills and several houses nearby. I want to make something like a big board maybe 10x8 ft bolted to a old trailer or something. It would be thick, maybe thick wood boards stacked really thick or something. It would have to be able to keep the bullet from passing through or ritocheting. Anyone ever done something like this, any ideas?