Sadly there's no bulkhead on the garages, I'd wanted to do the same before but 'wall washers' are the only option. Actually I still have a screwfix HI/LO bulkhead fitting with motion sensor and dawn/dusk sensor with a GLS filament bulb that's never been changed in 15 years
it's on every single night. Been wondering if this is a bit of a drain, I think it's a 60w bulb but on 'Lo' its probably 15w until the motion sensor switches it to 'full monty' ....you can't buy these anymore...I wonder why? 
I might stick a 'dimmable' GLS LED replacement in it.