I would be happy to use the first two as endpapers, not sure about the last two.
I have also set about the double weave book. Years ago (I think 7 or 8) I thought that, if I wove a two faced fabric which was 6 inches wide and changed over every 6 inches, I could insert pieces of board to stiffen the pockets up, print on them and have a concertina book. I made sample of 4 pages first and that worked fine but the method broke down when the producer of the transfer paper went broke. Also I did not like the design. So it all got shoved in a cupboard. Recently I have sorted out all the problems and finished the textile (woven of Tencel), including cutting board to size, inserting it and sewing up the pocket and am now ready for the transfer. I have practised and it all seems okay. Lots of layout in Photoshop. Tomorrow I start on the ironing.
The other (very odd) thing I have been doing is attending an online University course on ancient Japanese bookbinding. Very salutary. The room echoes to cries of 'I did not know THAT' . The data rate is high. And it is free. It lasts three weeks and you get to through to