I don't understand your question. You "need" GSX L2, only if you are interested in:
- Animated passengers.
- Replacement SODE jetways with the ability to customize airports.
- The Fuel Hydrant.
These are the only things that you can't do unless you have GSX L2. But once you have GSX L2 installed and Activated, there are no other prerequisite to it.
You surely can apply markings to all jetways, except for the default replacement model, because that model already comes with embedded markings, since it's supposed to be exactly the same as the default one, only much better looking and working with SODE. So, THAT particular model has the marking checkmark disabled, since they are always visible, but for all the other models, the markings are an option that can be turned on/off.
