I mounted mine just below the dash and above the center engine cover. Easy to see and reach from the driving position. The velcro was used at the top of the gauge. It fits tightly in this space and the excess wire is pushed behind it after using wire ties.
Installation time about 4-5 minutes, then you just program the gauge.
2013 Forester #3051SF
2009 Toyoda Tacoma (toad)
2010 Newmar Dutchstar (Sold)
2011 Fleetwood Bounder (Sold)