As I read the
manual for the TVPRAMP1R, they make an ambiguous distinction between the power injector and power unit.
I believe they are speaking about the unit that plugs into the AC power outlet, not the injector that is connected to the coax. If the power unit is at an angle, it may not be in the outlet far enough to get power.
As long as the connections are protected from the weather, I think you're fine.