Oh! So instead of building a "grid" like graph paper, you put down your sandbed and then push "slices" of pvc where your LR is going to go. And the swiss cheese holes alllow the critters to roam around. Do I have it right? (Actually that's what my husband said to do. Good thing I said "Sounds like a good idea. Let's think on it". Instead of saying he was crazy. Otherwise I'd be eating lots of crow this weekend.)
Sound's easier then measuring out pipe to fit around my overflow, not too close to the glass, etc. and lashing it.
Any other ideas from others are still welcome.