Co-Motion Periscope (large) may fit the bill for you.
Ultra-adjustable for pilot/ stoker with the 'seatpost-within-a-seatpost' standard setup.
Optional adjustable PILOT stem would take car of a tall person for extra reach. By getting leaving steerer tube uncut should give you the height you need as pilot.
May be worth looking into . . .
May still be a bit pricier than Mel's housebrand; having said that, have know Mel for decades.
He is a great/knowledgeable guy to deal with!
Pedal on!
Rudy and Kay/zonatandem