Full-timers and those with more robust system will likely want to install 12v power outlets in their van. Doing this means one can move electrical items around and plug them in where you want them.
If you must use a ciggy port considering plugging in a wired extension/splitter as a sacrificial lamb. *When* the port dies it will be the replaceable extension and not the built-in port. The *wired* part is important, since it will flex and place no strain on the port.
Ciggy outlet power is typically limited to 10A (~120w).
If you wanted to extract more power from the alternator you could wire in an isolator (plain solenoid or VSR). Instead of feeding an auxilliary battery this isolator would be used to pull more current into the living area. You could run 12v loads directly, or attach an inverter's input wires to the isolator's outputs.2)
Advanced users often cut off the ciggy plug and use something superior for their needs.
The most common non-ciggy connector is the Anderson Powerpole.