You're wrestling with the same set of trade-offs that haunted my eventual placement decision. I decided that if I was going to block off any airflow to the engine the least hurtful spot was the cylinder below the head. The supermoto front fender that I use sucks for protecting the headlight from tire spray but it's got some nice slots in the rear for directing airflow to the cylinder head.
At some point I'll replace the stock headlight with a Buell Uly unit that I found. The bracket for same will include mounting an Earl's oil cooler atop the front fender in Dakar fashion, but I didn't want to get bogged down in a major re-engineering effort with riding season aproaching. For the time being these little Baker Precision units are just fine - cheap, stout, easy to plumb and pretty easy to mount. If I wasn't such an anal-retentive nose-picker I'd be happy as a clam with what we've got, but hey, I like wrenching on these pigs almost as much as riding them.