Was there any means for aircraft to cross the railway which ran between the airfield and the hangars?
Yes.
"Another interesting feature of RAF Sealand is a facility to allow the safe movement of aircraft across the railway between North and South Camps. Sections of tarmac survive to the north and south of the line of the former railway and there are also traces of crossing barriers, to prevent accidental collisions with passing trains."
Clwyd-Powys Archaeological Trust - Projects - Recent projects - Airfields