I made a panel behind the engine to give me a surface to mount things on. I think Sean's car has something similar. I don't have anything special to seal it from rain. It could get wet, I suppose, but not soaked. The electrical plugs seem pretty waterproof, which they'd need to be to work on a bike. I think the harness pretty much dictated where the components would go, or at least the max distance from the engine. To put it someplace like the cockpit would have meant splicing, etc.
Oh, and I did use a lot of rubber, cushioning and isolation mounts for everything that I didn't want to be shaken to an early death.
Here is a picture before the wiring got cleaned up.