Just go to the editor, spawn a BLUFOR unit (important, cause if you just want some copy-paste testing, my code assumes BLUFOR for equipment).
Then find some way to run the code provided in this gist or also as an uploaded file : paste in the code windows and execute, add as an action to init.sqf, or whatever.
Gist : https://gist.github.com/anonymous/4f22bb11ebaed717c965
Finally, find some way to play with adding more stuff to inventory, like putting a Grenades Ammo crate on the map or using scripting to spawn stuff with little mass.
EDIT ADD : if you perfectly followed the above instruction, you can reach the seemingly maximum of loadAbs == 1324 by executing this two commands :
(backpackContainer player) addMagazineCargo ["DemoCharge_Remote_Mag", 6];
(backpackContainer player) addItemCargo ["Chemlight_green", 2];