OMG. that is crazy! is that even canon? very silly, but i like the design of it.

i would argue for the emperor to have some sort of special star destroyer, just to add variety, he has the royal guard, why not a royal destroyer? makes sense though as you pointed out to begin the concepts with what we already have. when vader flies in at the start, he could fly through the drydock when the star destroyers are there, to ready establish the scale, in order to reach the smaller dock which we see him in