We use our laptop while travelling in our Westy. The screen is large and bright and in full color so there is no compromise. The software is Delorme TopoUSA so we have all of the details down to 25 feet. The GPS receiver is a Delorme Tripmate - not the best but cheap (at the time $50 US). By setting the laptop on the floor between the driver and passenger and opening the laptop so that the screen is flat on the floor, we can both view it at a glance and it is well shaded so the display stays bright. The GPS receiver itself fits behind the poptop latch under the fiberglass poptop. This doesn't seem to diminish the signal by any significant amount. I run both the laptop and the GPS unit from the 12v cigarette lighter receptacle.
Larry