Next investment with 30-50k

I have a successful Airbnb that is nearly 100% passive. Brings in roughly $1,000 in my pocket each month after expenses, manager, and mortgage.

I have $30-50k to invest. I’m not sure if I want to get into another Airbnb, get into a small business (storage, rv, laundry, car wash, etc.), or something entirely different.

I’m looking for something as passive as possible.

Suggestions? Ideas? What would you do?