becuase it's a dream. Do you really care about the distances that much when you dream? Why should Mad Godhead care?
Also, it is a logical certainty that only an infinite space can hold an infinite realm.
The plane(t)s, moons, and realms are all infinite in size. They appear as bubbles in the greater infinity of the void of oblivion. (Yes, one infinity CAN be larger than another, and one can logically contain another. It is provable mathematically.
)
This means that if you were to attempt it with a vhekship, Sunbird, or an imperial mananuaght ship--- it would have to be capable of traveling at an infinite velocity, if you EVER wanted to reach your destination, otherwise it would take an infinite volume of time to reach it.
TES cosmological physics have so many fun consequences that nobody likes to think about.