If the seal on the drive shaft at the final drive unit is leaking, it's possible for the oil to travel up the shaft area and leak out of the rubber boot. If that's your problem, the repair requires removing the final drive unit (not the swingarm). It's not especially hard to do, just requires some patience to get the drive shaft and u joint back togather when reinstalling the final drive. A search on final drive oil leaks should provide enough info to allow you to replace the seal.
The seal is commonly available from the dealer for about $10.
Just the rear wheel and the final drive needs to be removed. The drive shaft will pull out from the swing arm with the final drive. You would then need to pull the shaft from the final drive and the seal will come out with the shaft. Installation is just the reverse with a little lube on the seal edges.
While you have it apart, it would be a good time to grease the drive splines and final drive splines.
just a tid bit here--all oil levels are check with bike on center stand !
if its 80-90 rear lube -- its rear dive seal---if its engine oil --its rear main shaft out put shaft seal . ( the one that the u-joint slides on to ) just my tid bit.