I remember when they came on the ultras, the dealers were taking them off because of them not letting the air get to the motor and causing heat problems.
I looked up part # you posted but could not find them.
Older Guy
Both fork air deflector part numbers show up via a Google search with several vendors and HD listed. The first (mine) has been superseded by the second, but both are still available. The triple tree unit is 58520-79TC. Attaching it to an angle as above, or drilling a single hole for mounting to the bottom of the tree would work. I use a fork bag (91773-85) attached to the fog light bar,but will try the baffle tomorrow as I've got one here somewhere.
In the Service Manuals HD did recommend removing the under tree baffle when hot as you note, but I've run 'em without problems. What little air gets deflected goes down towards the engine's fins. There's not that much cooling coming off the cylinder head covers. If they did, HD would have finned them like Indian.
BTW, those wanting deeper sounding yet 49 State EPA stamped 80 db non-Cat slip ons would do well to source HD P/N 80495-07. They fit perfectly on the '14 FLSTNSE's, but are about 3/4" shorter in overall length. The stock heat shields fit, and so will the shorter 64806-07A's. They are no longer in production, but are available from stock at several USA dealers.