It's worth pointing out that to get from Corpach to anywhere other than Fort William involves a runround in Ft William Yard. Adds 20-45 minutes to the schedule depending on train length & yard requirements, especially as the yard is not directly connected to the Glasgow direction so the train would need to set back onto the main line. Also adds the requirement for a 2nd member of staff. With a product like timber where the margins are likely to be very tight in the first place, the additional time and staff costs may well tip the balance from being worth trials to being a non-starter. There may be opportunities for hiring in staff involved with the Jacobite when that's running, but what do you do when it's not?BSW who own Corpach have a major depot in the Midlands and rail ought to be viable over that volant distance.
From aerial images there doesn't look to be anywhere sensible to put an avoiding line in, so regrettably for timber to move back to rail would require either a substantial improvement in the journey time south of Glasgow to compensate for the extra time at Ft William, or a substantial rise in the costs of running the trucks. Would likely require both, to be honest. On the positive note, the points and ground frame at Corpach look to be still present and the sidings are still in the Sectional Appendix, so NR seem to be keeping the link on the books. From the photos I've seen there's a rather substantial amount of greenery in the 4ft of the sidings so it'd take some money to get trains running again. If HGVs get a carbon tax and a decent path could be found south of Glasgow (a Bi-Mode may well be required) it's not impossible that a solution might be found to the operational issues at Fort William.