The above posters are correct in that the receiver on the V6s is only bolted to the cross member and is not rated for use with a WD hitch. You can use one but you risk twisting the cross member which is not repairable. Curt makes a nice frame mount one that would work, I can remember the model number though. You could get the Lexus one but it is very pricey.
As for the hitch not fitting in all the way, are you sure it's not hitting the spare tire? The receiver is open at the end but it is very short and the spare almost butts up to it. My WD hitch would hit the spare until I cut about 2" of the shank.
