If you are struggling to think of hand signals remember that dogs pick up body cues too - for example I can cue a repeat "spin" by tilting my head. For take a bow I use a right hand "gun" pointing downwards in front of my leg.
Do bear in mind that you might want to sharpen up that "down" later... to me an instant down is so useful that it simply isn't worth having any cue that can be confused with it. For me it is bad enough having a dog that begs (sit up) every time I ask for a sit and stands on his hind legs (stand up) when I want a stand, they seemed like good ideas at the time but as my dog became faster at responding I really wish I'd chosen different verbal cues.
You might well find that Evie jumps at the opportunity of misunderstanding your "down" and takes a bow instead. But people always get a laugh when my dog goes into a lazy down (front end only) and I call "BOTH ends" and he goes right down .