This search might help to clarify:Six Lamps and Four Visions
It is said that everything we experience is nothing but the Five Lights; although that we only perceive everything as the 'solid matter' of the five elements, due to our habituation to karmic and impure vision.
I've recently posted the following excerpt by Vajranatha, which hints at some of this:http://vajranatha.com/excerpt/BonpoBookoftheDead.htm
And in Skydancer: The Secret Life and Songs of the Lady Yeshe Tsogyel
, Keith Dowman wrote something to the effect that a Dzogchenpa's (presumably who has completed at least the First Vision) everyday Vision would look like a hallucinogenic trip (i.e. we would begin to perceive everything as the Five Pure Lights of the Basis, as opposed to how everything appears to ordinary deluded vision as the 'solid matter' of the five elements) to ordinary people.
And I think that it's debateable regarding whether there are actually six or seven colors in the ordinarily-visible light spectrum
. So Six (or Seven) Lights makes sense considering that. Some Occult traditions speak of Seven Elements and/or of Seven 'Rays'. So I've always wondered if mesoterically there are Five Dhyani Buddhas and esoterically there are Seven Dhyani Buddhas. The Five Dhyani Buddhas are all within the Sambhogakaya, so maybe the Dharmakaya and Nirmanakaya are each a Dhyani Buddha in themselves, making 'Seven Dhyani Buddhas' total.Seven Dhyani Buddhas and "Elements" mentioned in H.P. Blavatsky's The Secret Doctrine
This probably doesn't quite answer your question about the Six Spaces or Dimensions of Samantabhadra though....