The manual present here is a vast resource for cloning vectors including vectors for gateway cloning, match your expression and destination vectors from the maps provided.
Article A Versatile Viral System for Expression and Depletion of Pro...
Here is a list of silencing vectors to be used in plants, some of them have kanamycin resistance (column "marker"). They are all meant for hairpin RNA expression
I'd suggest you to use type IIs cloning for this, such as the GoldenBraid2.0 Framework. Visit www.gbcloning.org and check the paper I attach. We have a set of ready-to-use tools for many plant biotechnoogy proposes, including RNAi.
Article GoldenBraid 2.0: A Comprehensive DNA Assembly Framework for ...