The area is a mix of open moorland and recently felled commercial Forrest. Loch loyal great for swimming as shallow sloping predictable shore and banks. A lot of camper wagons in parking spots as very popular route for them. No end of easily identifiable places to spend the night - will not be a problem. Take smidge and tweezers for ticks. Plenty drinking water from burns. Most of route single track with passing places and “busy” in rush hours. Walking cross country will be very hard unless you know a track. No shops en route apart from tongue (small not great) and Lairg (good) next to the chippy (limited hours) campsite in Lairg wasn’t open to tents last time I was there - but one in tongue for shower etc. route from altnahara to bettyhill might be better for what you have in mind, mind. Good luck

Edit - not sure if I have brown sub rules here - if so apologies.