Receiver mounted flag holder: Shimming flag poles?

[Tdbo]

I will be participating in an event where I will have some flags on my truck.
I purchased one of these:

https://www.amazon.com/dp/B0C9TJ3L1K/ref=twister_B0C9TCGBX1?_encoding=UTF8&psc=1


Received this today. I have one flag pole that I have had for years, and purchased two more that were comparable.
I attempted to trial fit them, and even with two thumb screws, found that the poles are more wobbly than I would like.
This seems to be a common problem with this style of mount, as mentioned in the reviews for the several that I looked at.
Thus, the need to shim.
I had some scraps of pipe insulation laying around, and fit them in the flag holes.
While this firmed them up, I'm not sure if this will enhance integrity of the pole at speed.
Looking for any ideas regarding shimming up the poles into the mount.
Thanks in advance.

 

[Ranger83]

What is the OD of the flag staffs?

Ad says ID of holder is 1.65”

 

[nomas]

Cut a piece of sheet metal and roll it into a circular shape and slide it down into the gap .

 

[Tdbo]

What is the OD of the flag staffs?

Ad says ID of holder is 1.65”

The ones that I have are 1".

 

[Boomer]

Go to Harbor Freight and buy a container of plastic shims.

 

[Tdbo]

Cut a piece of sheet metal and roll it into a circular shape and slide it down into the gap .

This was the ticket. Thanks.

 

[Ranger83]

That’s what beer cans are for! Haven’t you read “Zen and the art of motorcycle maintenance?”