Making a mobile unit

Trying to think up ways to enclose a detector board on my truck and run the wires inside to a control panel. My thoughts are in getting an old marine type GPS unit, gutting it and installing a detector inside it, mounting it on the backrack on my truck. Then I can do readings from around areas I travel, dumps, railroad beds and years, tractor trailers on the highway, etc.. This is an example of what I have, now trying to get it open. I have one of them mini detectors boards and one of the smaller tubes and will be a perfect fit in it. Just got to get it opened.

http://www.ebay.com/itm/290895800095?_trksid=p2055119.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT

No problem, being in winter mode here, I like to think up and do up some ideas and thoughts for the spring. Don't have a cell phone, so thats out. only work 3 miles form work, only the wife has one just in case. Since I know, via hearing it, the normal click rates for my area, just mounting the detector part outside the truck in a dome type enclosure and runs wires into the cab to an LED and piezo clicker and power.

"...RadLog for Android/Phone/Bluetooth/Counter.", with gps function. YES!

Just need to figure out the best wire to use for the tube in the voltage as to not effect it too much. I know I read that adding a capacitor helps when using coax cable. Trying to use a more, flexible, smaller type of cable. Right now, here in the shack for the project I'm using a piece of shielded, 2 conductor cable that once went to the a temperature sensor from my old hearthkit weather station. Currently about 7 feet long soldered on the board and clips on the M4011 tube that is inside one of them GPS dome enclosure and working just fine, like the tube was mounted in the unit. But I will need about 10 more feet in length to actually mount in on the truck to reach the console.