I had a role previously as SQF Practitioner in a small third party treatment plant, company was small time family operation. They did 3PL non-food storage on top of treatment of food stuffs in the same warehouse suite. I'm talking everything from pool chemicals to children's toys to a small batch operation making fire starters. Luckily for me, the food area had been previously partitioned off with heavy shrink plastic from floor to ceiling. For them, this had been a cheap way to build a cleanable wall between food operations and non-food storage (about 70% of the suite was this non-food area). Upon going for their first SQF cert, I created the facility maps and designated the areas as out-of-scope, non-food storage for the separate business. All of our GMP's and other programs referenced practices to keep food from entering that area, and vice versa.
For us, the physical separation was so obvious that it was impossible for years of auditors to find any wild idea of cross contamination risk. You'll likely want to do the same in some manner, from a full dedicated aisle for this non-food storage, temporary fencing, etc. Bonus points if you can actually lock the non-food in a manner that regular employees cannot access the area. Your warehouse maps will need to be updated to reflect the non-food storage area. PRP's such as pest control and sanitation will need to be maintained around that space, and the products stored will need to be free from pest concerns.