PROPER WEARING OF LADIES' SASHES

Personally, I'd go with a fly plaid. I have only seen one sash that looks good on a guy; pleated and worn like a piper's plaid (but nowhere near as much material, so not as bulky; very important in Florida). I don't think 11" is wide enough to pleat, and I doubt it's long enough; a piper's plaid hangs down your back to the top of your spats (about 12" off the ground). If I were to wear it, I'd try to fold some shallow pleats into it, pin it high (brooch even with the top of my left shoulder) and let the rest hang free behind me, similar to a piper's plaid; like the woman on the left in the link, but backwards. This is what you're trying to emulate: RDMA Plaid Tying Manual

Oh yeah; I wouldn't wear a plaid in any form without a coat & tie.