At home, I pull past my driveway, then have to back the rig into the drive at a 45 degree angle, then another 45 around a bush up a slope, then through a gate, up against a wall to the parking space. My neighborhood is dark enough that it's impossible to see anything, and the boat/trailer effectively shadows the floodlights from the house. As such, I put some back-up lights on the trailer, using these.
I've got two pair on the passenger side, and two singles on the drivers side. At least now I can see what I'm about to run over, rather than sensing it and getting out and taking stock.