On the page 14, opposite of the Conditions Rules:
"Encumbrance
If your stalker is carrying more
items or Conditions than available
inventory slots, they are considered to be encumbered. While encumbered, the stalker
cannot run, moves at half speed,
and makes all saves with
Disadvantage."
This rule is changed from Mausritter, where you would discard an item to make room for the condition. I decided on a "video-gamey" solution for carrying lots of stuff as I'm not a huge fan of inventory management.