I bought a 2nd-hand 38" switchblade with a custom fiberglass enclosure that can fit a 12s3p 21700 (with P42a that would be equivalent to a 12s4p of 18650s) and ESC. It needs a lot of work done though.
I was considering this one, but still hoping for something more 40-41 - not only I feel better on longer decks, but also battery/esc space is important for me.
Nevertheless, if you thinking of selling it just post pic and name the price