Its a damn lift . thats how vader and luke reached the tower.

I imagine an interior to the down levels like this in ANH. but it stops somewhere

have vader reaching the tower via lamda class like one posted as cross section is a choice.

Give to the tower a reason to be up there. maybe its an antenna party and the tower a repair tower.

Make the tower as control tower that observes star destroyers can land on the top surface for repairs.

find something handy and be able to show it to the audience or just re position the location of the tower to avoid further alternations and headaches

-Angel