@gt94sss2 in the best case, following the public road, the current route, it could be possible to knock about 0.84 mi off the current length, but no more, because there is no civilisation closer than about 3.707 mi by public road from my house, the northernmost house in Heasta, to any kind of civilisation which I have taken as the Harapul cattle grid.
The straight line route from the back of the the exchange, which is entirely doable, straight out onto the moor and heading up to the W of the Fireach Clach, the highest point on the road cuts about a mile off the road route.