I am afraid that is hard coded by Squad. It can't be changed by changing a config file. What you would need is a *.dll file that overides the behaviour set by Squad. @Angel-125 has created code that has changed the behaviour of items being dropped or placed by Kerbals for a number of his great mods. So if he has time he may be able to help or set you on the right path. He basically had a sort of ground anchor before the main game did that was used for craft construction out in the field, for his Buffalo mod. @linuxgurugamer is also incredibly knowledgable, though very busy. He might be able to point you to information you need.