I have directly asked whether they got the bags, but my friend who is also looking for a B30 for his mother, tried the 'willing to buy other goods then ask' way and failed for all 4 days. Hence, if you show that you will buy other goods and they still replied that there are not any bags, I guess they really don't have any in store.
On the last day, I scored a KP and my friend asked the SA whether could help with scoring a B/K/C for his mom. He wanted to get a jacket and shorts, and already brought a blanket and a pair of sandals from him. The SA was very direct and replied that it is very difficult to score a small size B or K in Japan, as the japanese/ asian ladies are very petite and they prefer using small bags. My SA asked my friend to come back in a few month, but we don't know how long is the wait.
The constance bag i scored was just sitting on the shelf so sometimes you might find them just there without the need to ask any SA. I also specifically put KP and KC in my wishlist, as where I live get very little to none in store and I have heard that they receive a lot more in japan. As for rodeos, they do have a lot of stock, but for the PM size, they won't show you unless you are a VIP or getting other things.
I think we have a similar wish list color haha those are the color i wanted too, but my SA also mentioned that the classic color are most likely reserved to their local customers, therefore you might want to add some more seasonal color options in case you get offer.