It is somewhat reassuring to see that my confusion is not unique.
A trip to the local craft store has turned up one of those paper mache' birdhouses that is vaguely like a lighthouse, but square instead of round, and 12 inches tall. My plan is to not chop into it, but rather build a set of obviously mismatched scaffolds around it at a couple levels, construct a pair of shorter towers like it to connect the scaffolds to, and set it all on a single base that would define the null magic area.
The goal is to provide the high spaces for melee conflict with available but minimal sniper nesting.
Finding the time is my next trick.