Glenshieldaig Forest, out towards Torridon has a real in-the-middle-of-nowhere feel. Very wild, rocky, bit barren. Challenging little road to get there, not far from Torridon village and loch, also near to Applecross on the west coast. I think I would top up with fuel before heading up there, nearest garage on Shiel Bridge to Kyle of Lochalsh road? Not sure about water sources out there, but could fill a couple of bottles before you go. Torridon village has a small grocery store. Ground is very rocky and uneven, so might be better to bivvy rather than tent, if you can rig up decent midgie protection. I very much doubt that anyone would disturb you on that road, didn't see much traffic even in the middle of the day.