instead of hiding the attachment, highlight it.
Find the biggest lag bolt you can, cut the head off, slot the upper unthreaded shank to accept the paddle.
Attach your lag to post, then use a set screw through the slotted upper shank to hold the paddle.
Or
Run a block vertically on the post just under the paddle, drill a hole through paddle above block, attach with a bolt/screw vertically down into the block.