ness64 wrote:The nearest toilets are in Kinlochewe, could you maybe sleep in your car in the village carpark ...?
I'd be wary of that. I last passed through Kinlochewe towards the end of March, just before "lockdown" officially kicked in. Even then the locals had a makeshift barrier across the entrance complete with sign saying "Toilets Closed, No Campervans." I haven't been through since, but if "wild campervanning" has caused the same problems there as in some other locations, even sleeping in the back of your car may cause friction.
Plenty of wild camping opportunities in the area if you can put in the effort required for a proper wild camp well away from the road and your car.