Just have kakashi one day dress up as sakumo, and troll the crap out of village.
I'm sure he tell some people. The fact of having him walk around talking to people that knoiw and don't know who that is, and acting like nothings wrong.
Just have a Clone walk around as normal him. If Gai Stops him has Kakashi just say something i the lines of "oh, no. that's not me, you looking for my son" or you can just have him turn around and wait for rhem to realize.
And the fact of you can make it that the hokage knows your doing this so he doesn't get in troable. If he does though the fights that is going to happen since he's proably going to get sent out as Sakumo.
You don't have use most of the things I write down, but I just imagine him looking more and more dead as the days go on you as the hours pass(depanding on how long you what him to do this) to the point they just see him with a "injury" where he stab him self, and act like nothings wrong.
And when that's over just do that again around the same time.
Oh that's make such mayham. Even the fact of you can use an AU, that just makes things more fun.