I have been at this base for 1½ hours..
My final evaluation is:
It is, with the current content and build mechanics ''physically'' (without hacks) impossible to obtain the loot from the loot room of this building design. It is however possible to: Build a stairway up the side of the building to the roof, jump across the pillars onto the small ceiling, and place C4 ontop of the ceilings to let the damage from the c4 pass trough the ceiling, destroying the doorway, and then from the stairs throw grenades into the loot room, destroying the loot and sleeping bag, hereby rendering the base un-useable by the owner. However the amount of c4 require to destroy the doorway trough the ceiling is so high that this is very unlikely to be done by your average griefer/enemy. (50 c4 +-)
-Zhorty
You *CAN* get close enough to the edge to place the C4 from the ceiling onto the wall and blowing it out that way. It is then possible to fall from the ceiling, into that room.