I used to go to the Idian River Gun Range in Central FL and they had a culvert pipe set up like that. Out at the 100 yard berm there were 2 culvert pipes at the last 2 shooting lanes. The long range shooters would prove to the daily range master that they could stay on target at 100yds, then they were allowed to shoot the longer range. There was a small berm at 100yds that divided the last 2 lanes such that even the guy in the 3rd-to-last lane couldn't angle a round down into either of the pipes. Finally, there was a wall that went along the outside that allowed the long range guys to go address their targets without stopping other shooters. A nice set up. But yes, the big issue would be that the longer the range, the larger the pipe has to be.
