Actually there are a range of offsets that can be ordered with certain wheel manufacturers. I am not sure if the wheel he chose has this option, but Volk for instance has different offsets that allow the wheel to fit the specs for a range of cars.
As far as wheel spacers go they are still considered dangerous even though they are more technically advanced then the older ones.
I would start over with a wheel that allows me to get the offset right so the wheel is not so tucked..

 

Ah, ok. See, I learn something new everyday.

I guess anytime you add something in your drive chain like that you're adding weakness but they use these on big rock climbing 4x4's so I'm guessing they are fairly safe. Plus the ones I'm looking at are TUV approved so I hope that means something.

 

i have 20x8.5 in the front and 20x9.5 in the rear and it looks the same. yea i am gonna get wheel spacers too cuz that does look kinda funny.