I use the saddle tape. The insulation tape is good also. It will keep the oil out of the fuselage, and hold down vibrations too.

I have never used the RTV on the wing saddle but that is a good idea. Just make sure not to compress the wing all the way down while you are forming the gasket.

If this is on a slightly less than new plane make sure the covering is clean or you won't get good adhesion. I like to use windex and rub it down, then do the same with rubbing alcohol.

I tried the exhaust diverter once. I didn't have the tie wrap holding it on, and when it popped off the engine revved up a couple hundred rpm's higher. I have never put one on since. They rob too much power.