I have a 52" fence, but have columns that make full sheets a pain. The extra room on the side table is also handy to put sleds, etc... off to the side for a moment without having to put them on the floor.
A 50-52" fence can easily be cut down to anything less than it's full length (42, 64, 36...), should the craftsperson decide a shorter length is better. You can't stretch a 30" rail and table.
On another note, why mess with horses, etc... with full sheets?
Put the sheet on the floor, driveway, trailer, etc... on (2) 2'x8' sheets of 2" foam insulation, kneel on it and cut away. Most of the time, I freehand to a line and clean up the final edge on the TS. If you need to clamp a straight edge for a finished edge (or no TS is available), simply move the foam to clear the clamps. I cut my 2'x8' foam boards to 2'x4' for easy handling and storage, and I've been using the same boards for years.