I have the short nipple even with my skidplate attached. While I see your rationale, I wanted to minimize the possibility of anything hitting the nipple. Probably not an issue on the pavement but an unfortunate rock encounter on a trail is always possible. The oil drains out of the bottom opening - what looks like a side opening is just part of the valve. Note the black clip, which is an option. The lever goes into a detent when closed so it really can't open accidentally but Fumoto is smart enough to collect a few extra bucks from those of us who are paranoid enough to buy the clip, which prevents the lever from moving until the clip is removed.
On a related note, there's a plastic OEM piece that's supposed to cover that opening in the skidplate. I bought one at the dealer years ago and it was gone within a couple of weeks. Don't know if something hit it or it just fell off but it doesn't attach very securely so that was a $17 lesson.
This looks like it for $12 on eBay but I wouldn't waste your money.