good idea if it will work - I know most quick lube shops dont take the drain plug off cars, they suck the oil out through the dipstick tube.
If you can get a tube down into the bottom of the assembly it should work. Remember it is 80W hypoid, and tends to be thick.
Im not sure about the syringe, but some kind of sludge pump might work.
Another solution is to get two burly guys to hold the bike upside down... :^)