The Sandpiper was designed as a solo; it was never intended to be used as a tandem, and no seat placement is going to turn it into a tandem.
You can paddle it as a tandem, but I fear you will soon learn to regret that decision; as will the person acting as your tandem partner.
Any expense or effort towards making it a tandem will be wasted money and time.
Kayak Deck Gear Bags
Kayak Motor Kit
Full Size Sail Rig
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