Nice to see that I am not the only one who has just bought an old RD04 model recently.
I am like you keen to share info and get advice from other XRV (africa twin owner).
For stickers: a french company offers XRV stickers : AXESS STICKER autocollants, stickers, motos, autos (I have never tried them so cannot say if they are good or not)
For parts, there is a french website called www.leboncoin.fr where one can buy used parts for everything (including the XRV). problem for you, it is in french.
Hope this helps.
(from Bordeaux France)