So you can buy fan holders but they are 3d printed and will snap in days if your like me and using a 12-14″ oscillating fan. So I went to Menards and picked up Tool Shop 12″ Wall Mount Tool Holder.
I drilled out a hole an inch from the end, slide my fan in and bolted it tight. To help I added rubber in between the fan and the holder for extra stability. Then measure the width of the pole drill them out on the back of the Holder, this is where you add the U Bolt. Buy the U Bolt alittle bit wider then your pole, add a piece of rubber in between the pole and U Bolt. You can use zip ties instead of U Bolt but the weight of the fan will make it slide. This helped me out that I add this hack in all my tents.