Even though you "like to avoid object oriented PhP", you should really learn how to use object oriented design if you want to write large software. OOP in PhP is kind of tacked-on, but the tacked-on frameworks will still work.
The basic idea behind OOD is that a component should know how to do everything directly related to it, so you don't have to think about how the parts interact. For example, a Car would contain not only the parts (data) of a Car (like wheels, engine, steering wheel, location), it would also contain information on how to do all the things a Car should be able to do (start, drive forward, reverse, turn).
The potential benefit is enormous. If you need a Car object to do something, you don't need to use and maintain some function floating in global space. You just tell the Car what to do through a simple interface, which in this case would be the steering wheel, gas pedal, brake pedal, and gear shift.
If you spec what those internal functions do in an abstract way, a programmer using a Car object doesn't need to know how the engine works or how the data is stored inside the car to use the object (imagine if you needed a degree in mechanical engineering to drive a car in real life). All a programmer needs to know are simple instructions that explain what happens when they use the interface (steering wheel, etc.). As long as the implementation for those internal functions fulfills the specification, it's safe to program around it. If you have different implementations of Car for different situations (say, Sedan and Truck), the same code will work for both Car objects. More importantly, if the code needs to change because you find bugs, changing the code won't break the system.
I've worked in enormous systems that aren't OO, and it's a huge pain. Learning to approach from an OO perspective is something that will make your life much easier in the long run.