The seat the Waterlust was 'designed around' is this one offered by CLC. It's what my wife gave me for Christmas a few years back, even before my kit started to look like a boat. It's also what some of the other builders (at least here in the US) have chosen for theirs.

Farther afield than that I have no idea; there's precious little about this craft here on CLC's home forum.

If you've built one I trust your experiences would be welcomed here by those of us who've been adding to a thread (an epic one, I assure you) on the forum hosted by Fyne Boat Kits in the UK, a marketer of some of CLC's designs among others.

You're most welcome to look in on that thread – it's a long one, begun early in 2020, currently numbering 42 pages with copious pictures – and join in of course should you be inclined, once you register under the forum's rules.

   After trying a few different seats in my WaterlustCanoe, I've settled on an Ergoboost seat from Pelican Kayaks. Designed for fishing, it has a sittin place on the back of the chair back. When the chair back is folded closed, you can sit perched up a bit higher to be ready for hiking. I cut haif-round notches in the boat's chair rails to accomodate the seat frame securely.  It is comfortable for pedaling and works great for sailing.

This one? Interesting. Thanks for posting that!

I'd like to know more about your experiences building then using your Waterlust. Where do you hail from? (If you don't mind my asking!)