Check the owners manual for the back-up screen. Generally, LCD screens don't like excessive heat or cold. Putting it in front of the vent exposes it to both, severely shortening the life of the unit. If it condenses (after a while being blown on by the A/C then sitting as the car gets hot while parked) it will go south even faster. Note in this "before" picture directly below, I had my XM radio there. I moved it pretty quick.

As for wires, I started out with quite a mess and a GPS on the dash.



Then I looked at the service manual and found a few things - the a-pillars snap off and have enough room to conceal pretty large wires. There's room in the dash and access from both sides to fish wires from below.

Panavise makes a bracket for the Crossfire that's easy to install in a few minutes with a screw driver that will support a GPS. It does not interfere with the glove box or air bag.

More Info
Many radar detectors can be mounted on the visor with a clip and the wires run under the edge of the headlining to the a-pillar.

There is a phone bracket mount that is on eBay that will mount to the console to the right of the stick without holes that would allow a cradle with power to be installed and the wires concealed. Another easy install.

I don't have the phone thing (it's bluetooth and I leave it in my pocket, comes through head unit) but here's what mine looks like with GPS, LCD screen, and radar detector.





More Info...
(I removed the little screen visible in this shot and integrated the iPod and XM radio into the head unit.