that is the drain for the crankcase. don't really want to fuck with that, it will only give you a couple oz. and it's a pain to get back in without cross-threading. look farther back.
02 Pit Bull, tank under the seat. Round cap on the oil tank is a knurled cap, about 1 1/2 inch, ya can't miss it! I'm thinkin the Mastiff is probably pretty close to this On my pit I can unclamp the drain tube from the frame, and swing it out enough to take the plug out and not drip oil all over the frame! Got faith in ya guy! You can do it!
Like davidg stated it helps with bike in the air. It is somewhat a pain in the ass without a lift. Also, can make a big f@cking mess.
awg has the best solution plus buy you a scavenger.