One that gets frequent recommendations on the largest recumbent owner's site is the Ventesit pad. It comes in many versions for different recumbents, You can see examples at the Hostel Shoppe in Wisconsin
https://hostelshoppe.com/search?type...ventesit*+pad*. You can ask them if there is one for your bike. There was an earlier post on this very subject in July 2021
https://m.bikeforums.net/showthread.php?p=22126492