If I remember right, the only real clearance issue directly above the drain plug hole is the oil pickup tube, and that's probably 25mm or more above.
What you can do is measure. The next time you change your oil, or if you want to check it between oil changes, drain the pan and then stick something like a wooden dowel or aluminum pin straight up the drain plug hole until it touches something. Mark it at the level of the drain plug threads, pull it out, and then you'll know how much distance you have to work with.
I wouldn't fret over an extra 5-10mm of length on the drain plug, personally.
BAHNST is definitely right about staying away from the cheapies. Usually the cheap Amazon/Ebay specials are aluminum plugs with a magnet glued in, and the glue will break down with heat cycles until the magnet pops out and goes wherever it wants in your engine.
