My 16HP riding weed wacker
Here's a fence trimmer I build from a large wheel gas powered string trimmer. It clips on to the mower deck mounts with two pins in about a minute. The original had a 6HP engine, so I geared it up a little and usually cut at about half throttle. The mower height lever raises and lowers it, although it could use more range than the mowers 4 inches. Sure does cut great though. It's spring loaded and pivots around fence posts.