If you look at a lot of the Japanese cars they go for the 'wheel outside the body' look.
I've noticed a lot of the cars in HyperRev etc run 9.5 +12 up to +22 for R32s, though they seem to protrude a bit.
IMHO it looks a bit odd, and having popped a guard in one of my old cars I reckon you want to stick to somewhere around a +18 to +22...
geez I envy the hard decisions you have to make lol