I fitted a large capacity Scottoiler behind the rear registration plate. The large capacity unit holds sufficient oil for 5,000 miles of riding . To make the system robust when off-road I simply drilled a small hole in the top of the front sprocket cover and drop the oil onto the chain inside the plastic cover. Its clean (as any fling happens inside the sprocket cover) and the oil line is out of the way of off-road debris and rocks, flailing feet etc.
When I rode from UK to Morocco I rode with it on normal setting through France, Spain and the first tarmac in Morocco . In the south, in deep sand I turned off the oil flow and wiped off excess oil from the chain. When getting back into highway I just turned it up high for 25 miles and flushed all the sand off.
I run my chain a little looser that specified, especially in the rough with luggage on the bike where the swinging arm movement is close to maximum. The last chain lasted more that 25,000 miles, during this time I only adjusted it 5 or 6 times.