Narrow roads in north Scotland

TravellingGeo

next summer we are hoping to spend 6 weeks touring the very north of Scotland with our caravan. I see on the road maps that most of the main roads are single track which sounds interesting! Our route would be up the west coast to Durness then head across
the top to John O'Groats then come South. Can anyone give advice on these roads and any that should be avoided at all cost !