I recently completed a scratch build of the longboat posted by Allan above. The boat’s rigging shows a number of interesting features:
1. The gaff is quite short relative to the boom.
2. The boom is thickest at its outboard end tapering to where it attaches to the mast
3.There are no backstays. The mast pendants provide this function to a degree.
4. The main sheet horse passes over the tiller, allowing the boat to be tacked.
5. The jib halyard passes through a cheek block.
6. A triple block near the masthead serves several different
functions.
7. The mainsail is loose footed.
Without going into details, engineering analysis indicates that these features all contribute to practical rig.
The Fore and Aft rig by E.F Thomas describes two separate single masted gaff rigs; the short gaff rig and the long gaff rig. Thomas believes that these two rigs had separate origins; The short gaff, the shoulder of mutton rig, The long gaff, the spritsail. While Thomas’s classic work was published in the 1930’s there is also a much older relevant work; Daniel Defoe’s. Robinson Crusoe. While Defoe’s book is a book of fiction, as a “merchant” he was required to sail with cargoes, so would have been familiar with boat rigs. Throughout the book, longboats were described as being rigged with Shoulder Of Mutton rigs. Robinson Crusoe dates from the early 1700’s. There are also drawings made in the 1720’s of various Colonial American ports showing boats with these short gaff rigs.
It is my theory that the short gaff as a boat rigs is the older than the long gaff.
My Model

Re; The Anatomy of the ship drawings: I am in general unimpressed with the boat drawings that they include in their books. It often seems that they just include something to give the modeler a complete package. The two masted rig looks Nineteenth Century.
Roger