Import some items from Vuforia Core Samples for User Defined Targets in Unity

I am trying to make an Augmented Reality app which uses the User Defined Targets feature of Vuforia in Unity. To implement it, Vuforia Core Samples need to be imported in the project which is around 100 MB in size. I am using only the UserDefinedTargetBuilder, UserDefinedTarget, TargetBuilderUI and SafeAreaManager shown in the Hierarchy (basically only the objects which are there is the sample UserDefinedTargets scene) except the models of Astronaut etc. I tried importing some selected files only but that gave me many errors because I think there may be some (or many) callbacks and object references which I did not import.

I want to import only those files which are required for User Defined Targets so that I can reduce my apk size but don't know which files to import and which ones to ignore.