First, I couldn't be happier with my BMV-712 (had to beat Titan Mike to the endorsement commission!!)
Second, don't worry about the display, you get everything you need and more through the Bluetooth app. A number of us have literally stuck the display in a zip lock bag and left it tied up under the chassis somewhere. I would suggest doing that for your first couple of trips and see if the app works for you (ummm, spoiler alert, it will . . .
). You can always hook up the display later if you really want to.
The shunt just gets mounted near the negative most terminal of your house battery/batteries. I just mounted it with two self-tapping screws to the side of my battery bay. You will need to purchase a short battery cable to go from the negative battery terminal to the shunt (just match the guage of your other cables and you should be fine). EVRYTHING that was previously connected to your negative battery terminal now gets connected to the load side of the shunt. Very easy install.
There are numerous other posts on the Forum about other aspects of the BMV-712, so hit the search button and see what others experiences have been.