This stuff is widely recommended for gluing these things on without using the screws. Available at places like Home Depot. I've had no issues on two bikes and 50K miles with no-fastener installations. I do think it is a good idea to remove the fender to be able to properly glue and hold it. (Which was easy on a FJR, but almost required a front end disassembly on a Strom.)
This mod is essentially the motorcycling equivalent of mud flaps on a car. Hardly a "must do", but it does help a lot to keep things cleaner. And for bikes with with low-mounted oil coolers, it really helps reduce the abuse they tend to get.
- Mark
This works just as well. The Devcon Plastic Weld is undoubtably the same material, but is more viscous and fills voids between the parts.
Paul