Just mine knowledge about bags; you can put a bags up to 39 cm, but then you have to relocate the blinkers - turnlights.
Or, like this store is recommending the saddle bag for gz
http://www.louis.de/_303f7ee6547ebc3c7c ... r=10025217
Looks like the form of the bag is allowing (even though it's 40 cm) to be mounted,l i prosume without relocating the turnsignals.
Guys from other forum suggested to me, to draw the bag (according to measurements) on the thicker paper and aligning it to the bike. If it goes, but it's not going well with the holders, then you try to make a holder of your own or some one else makes it for you. But first the measurements of the bags are top priority. Relocating the turnsignals is PITA said owner of gz to me, when i talked to him about that.
just my 2 cents...