Another vote for upside-down (yes, tweeters down). I spent quite a few years in the same situation, where "on a high shelf" was the only option.
Get them as far away from the wall as possible (even if that only means having the front edge of the speaker an inch or so out from the edge of the shelf), and if you're angling them down try to rig some kind of safety setup so you don't slam a door one day and have one or both slide off onto the floor
And welcome !!
EDIT -- hmm, turning them upside down only lowers the tweeters by about 3", so maybe not that important. On the other hand they do seem to be small enough that you have all kinds of mounting options including maybe mounting them under the shelf (depending on whether it's a shelf or a big-ass wall unit).
