Help with new wheel setup

Hi guys, this is my first post and I've always been wanting to do this setup on my black on black 2012 TL SH-AWD, currently all stock. but just ordered Tein SA's and will likely roll fenders as well. I've put down a deposit for Savini BS4 rims... 20"x10" all around, the tire guy says offset will be +40 and will give 3.5" lip, for the tires he says best bet would be 245/35. My main question is could I go lower offset... I really want 5.5" lip but he says this wouldn't work for this type of vehicle... What do you guys think ??
Sorry for the noob question but your suggestions and help will mean alot..

Iv'e attached a configuration of how the wheels would like like on the 4th gen TL... along with the rim.

Thanks for your time. :)