I agree w/ 61: "BTW, great sounding rooms don't have to conform to golden ratios." You can certainly find hundreds of articles/advice on GS rooms and acoustics (type: "golden section" and acoustics into Google) but resonance and harmonic frequencies depend on multiples of a room's dimension(s) whatever they are. The whole "Cardas thing' just cracks me up! (BTW, I have a degree in architecture and acoustics, AND my last name is Golden, so I've certainly delved into the subject ;-)
I have two recommendations however:
1. I strongly urge you to set your speakers up on one of the long walls. At 16 feet, the room width is just a bit more than the minimum (15 feet) required to do this. And save that 32 foot length because with the L/R speakers far from their respective sidewalls, secondary reflections will arrive at the listening position too late to mess up the sound stage, so the usual sidewall absorbtive treatment will not be required. Large wool area rugs, without padding, are the best acoustically for the floor. Furniture can do the rest if it's upholtered with fabric, nice and plump, and enough of it ;-) A bookcase with a couple feet of walk space between it and the back of the listening sofa/chair will provide a perfect abffusor for the rear wall.
2. The other thing that could be a problem (or not at all) has to do with the low ceiling. Whether it's a problem requiring treatment, or not, depends on your loudspeakers. Line arrays (Pipedreams), d'Appolito arrays (Dunlavy, Dynaudio), ribbons (Dali), and panel dipoles (like Maggie, MartinLogan, SoundLabs, etc) tend to radiate mostly horizontally and very little vertically. So ceiling reflections (that bounce back down to the listening position) aren't significant. Otherwise, you need an absorbtive panel about 12 feet wide (L to R) and 6 feet across on the ceiling halfway between the speakers and listening position.
Just set up the speakers and listening position first as Onhwy61 says. Most speakers (not just dipoles) need to be at least 3 - 4 feet out from the wall behind them. That's pretty much it ;-) I sure wish my room was 15 feet wide so I could use the long wall - it makes acoustical life so much easier!