So I tried lowering down the side fences by 20mm and it looks decent.
I also went to check what is the length of the bamboo that use to make the bamboo base. The length is 560mm, so when it puts beside the fence and compare, it shows that the placement of the metal pole that use to link both fences together when in the formation of the chair can be place up to any column by the 5th column(as shown in red) and so can be hide under the bamboo base.
So currently I am making the second mock up. Will update again when I am done with the second mock up.