Nice job. One of the reasons for doing a pan in the first place is to cover suspension components so if you can drop the pan down a couple inches and still have suspension movement that would be ideal. Personally I cut it out around the wheel wells because I didn't want to deal with it.
Second, if those are aluminum bars make sure you're putting something between it and steel frame parts. Al and steel will react and corrode. Also, I know rust is not as prevalent in the PNW as here, but you might want to coat those metal screws with primer... it might be better than nothing.
The diffuser should be flat and level to the ground.
Keep it up!