I was able to secure a set of plastic high-voltage transmission towers on Amazon. They were easy to assemble, and they're big, especially next to my little 15mm wasters - I didn't think to throw in some miniatures for scale, but the bottom cross-piece probably comes up to mid-chest on one of the figures.
I used a heat-gun to soften the plastic enough to make them lean in a properly post-nuclear fashion.
The only downside to these is that in the real world, they would be so far apart that two of them would never appear on my game table. I'll just have to use the power of IMAGINATION to justify having a row of them towering over my buildings!