It can't easily be faster by flying lower though, certainly not on arrival - it's tough to beat something dropping from 5000km up when you're dropping from 100km up, unless its accelerating rocket sacrifices a lot of potential lifting capacity to get it there - as Topol does, making its ascent rather easier to see.
Ensuring accuracy while never fully leaving the atmosphere to allow precise star sightings and a known geodesic track will be a challenge too.