Rocket Small Tail Packs, Whats The Best?

For that sort of weight/size, i'd go for a kriega us10!
Or even, kriega rucksack possibly?

 

Kreiga US10 is small pack with zip top stow and full waterproof. Roll bag. I love my US20 and they can be strapped together.
Just returned from a trip with 2xUS20 side by side

 

I use the Triumph tail bag that has a “foot” that slides under the pillon strap . It’s good for me as a back rest as well. 2025 gt storm was the mat blue and black changed it a red / silver color scheme.

 

From SW MOTECH you can also take some small bags with rollable close function and very good straps to attach it on the GT.