Is it safe to parallel connect components to a single to a 12v DC PSU?
Yes.  The power supply will make 12 V as long as you don't exceed its current rating, which you say you know you won't exceed.  Otherwise, 12 V is 12 V, regardless of how much current someone else is drawing from it.

A related issue you should think about carefully is voltage drop in the wires.  The power supply will do a good job of making 12 V at it's output, but that's not the same as 12 V at the other end of a 18 guage wire across the room, especially when something else is also trying to draw power from the remote end of the wire.

Think of the wires as series resistors and plan out your system accordingly.  The resistance of various sizes of copper wires is well documented out there.  Remember that you have two wires, + and -, so the total series resistance seen at the end of a cable will be twice that of one wire.

You can trade off losses in the wire, voltage drop at the end of the wire, number of units fed from a single cable, and thickness of the conductors.  There is no single magic answers.  It is up to you to pick the best tradeoff, where "best" is measured by a weighting of factors that only you can decide.