Does anyone out there use 5" fittings in a Thien baffle?

I've got an HF collector and I'm making a separator with a 30 gal. can and I'm having one heck of a time finding fittings! I can't find DVW in 5" and schedule 40 prices are outrageous. I've seen 5" elbows for over $100!!!

Lowes has the metal 5" adjustable elbow but, I was trying to find something with a smooth interior (does it matter?).

I'm willing to go with metal or plastic...

If anyone can steer me in the right direction, I'd forever indebted!

Here's what I've got so far...

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