Here are some before and after shots (left and right respectively):
The interior of the warehouse now has more nooks and crannies for infected to pop out from, as well as a raised catwalk that the survivors will have to traverse. The high windows at the far end also give a sneak preview of the barracks, foreshadowing one of the main locations of the campaign.
Finally, I managed to retain the gas station's shop in all its glory! Very pleased with this for reasons mentioned in the previous post. Admittedly it's no longer a gas station as the pumps were removed altogether, but the store itself is the same except for having a flat roof instead of a sloped one.
So all in all the changes I made over the last two days have achieved the following things:
1. The placement of buildings makes more sense from a logical perspective (they're not too close together and impractical).
2. The taller buildings help occlude more objects from the player's view, helping to keep frame rates nice and low.
3. The survivor's path is now a bit longer and more winding, helping to pad out the length of this level.
Lessons learned: Don't be afraid to cut content if it's not working! If possible, try to retain the elements that do work but not if they compromise the bigger picture.