It helps to have the radar turned on while going through construction zones. The unit I have is covered under part 15 of the FCC and only transmits with 100 mw. I have the video in the car due to putting up with too many so called "professional" drivers that don't know the first thing about driving safe. I'm sure Motor Carrier Enforcement would like to see some of the video I have had in the past. I have also been told that if I have video of an unsafe driver it can be turned in and will possibly be investigated if the video is clear, the location can be determined, and if license numbers are visible. Law enforcement would review the video and if they feel it needs to be further investigated it would be turned over to the prosecutor for the county it took place in.
Don't worry about all the naysayers here. Obviously you are gadget person and I'm on your side. Gadgets you use don't have to be a necessity but if you enjoy using them then go for it. You only get one turn on this world so you might as well have fun while you are here.
Among other things, a radar unit can take the boredom out of a long trip. Seeing how far away you can pick up an oncoming car is a challenge. Setting the mode to 'stationary' while moving to see what the highest combined speed you can get is always fun to do. After awhile you will find that by listening to the Doppler shift audio you can almost always guess the correct speed of an approaching vehicle without looking at the display. Obviously folks may think I must have one but I don't - I have many. No, I'm not a cop but I do work on and install the dang things along with everything else that goes in a patrol car so it to my advantage to see what they can and can't do with them. When I get the interface set up I will be able to put my speed and the target speed on the display of my Kustom Eyewitness video system in my old '87. You never know when you might get something that will help you or someone else later on.
Give the OP a break about how he sets up equipment in his car and that also goes to 'if-you-don't-drill-a-hole-in-your-car-you-are-going-to-hell' crowd. If he is happy with his setup and it does what he wants, leave him alone.
My 2 cents...