Need diameter of rear down tube on radwagon4

[aegert]

Hey thanks for any help here RAD is of none. I have a RadWagon4 I put a custom seat on the back deck. I wanted to ad ATV 6 foot chaser LED whips to it for Burning man. The bike is in my container out in Gehrlach NV I'm in NY LOL. Looking to see if anyone with a bike can get me the diameter of the rear down tube on the RadWagon4. this is the tube running from the rear deck down the bike . On the orange bike its orange with a blue stripe so I can build up brackets or clams . the existing clamps fit 1.75-2".

The tube in question is circled in the attached pic thanks!!!

Any help is a blessing thanks in advance!

Adam