Lexus doesn't make things easy for the amateur radio operator. Gamber-Johnson makes several mounts you might want to look at. They typically bolt to the floor and sport two or more universal joints to allow positioning of the rig. As for the wiring, if you don't want to do it yourself, go to a local sound shop and ask them to run the wire directly to the battery. It will require drilling the firewall.
Alan, KØBG
www.k0bg.com