RehabMannie - what if you allowed them to specify the “donation kits” in an ini file? It might default to a setting of 0 (which gives specific icons). But if they change that setting to a different number (1, 2, 3 or 4, etc) then it would provide different items in the “donation kits”. You could provide essentially unlimited options using that method. OR you could provide a dozen options to turn specific items off (i.e. ModDonationKitSaddlesEnable=True, ModDonationKitArmourEnable=True, ModDonationKitWeaponsEnable=True, ModDonationKitAmmoEnable=True, etc). If they want to turn off saddles or armour being in the donation kits they could just change the relevant flag in their ini file.
I found this guide useful for getting data from the GUS.ini file: