In American Law the Mormons are allowed in the U.S. and by their religion they are allowed under U.S. law more than one wife.
All the laws that the Biblical men lived by does not apply to us as our law does not apply to them.
below copied from your post
"But it is possible for a man to have multiple women and still be right with God even though the best way is one man and woman?"
the above statement may depend on the religion you choose, under the Baptist you might be guilty of adultery and at same time not guilty of breaking any U.S. law.