Honestly? I don't see that working too well. I kno those are all safe on the compatibility chart, but the chart was written with the intention of just adding a FEW extra fish in the tank. In other words, the tank should still be focusing on the seahorses, and a couple fish are there for variety. You mention a school of wrasses, and a couple ocelaris clowns.....one of each might not outcompete for fod, but the qty you're talking about would almost certainly outcompete the horses for food.
I'm not tryin to bust on your dream (esp the painted backdrop! Coolness!) but just suggesting if you do it, go for 4-6 horses in a 55g tank and just add a max of 3 fish to the list: maybe a fairy or flasher wrasse, a firefish, and a mandarin if you have a fuge to support it that's been running a while.
I know percula clowns are listed as horse safe, but just remember that clowns are damsels in disguise, and sometimes act very aggressively towards tankmates. i would do one if you really wanted, but watch it and be prepared to move it, just in case.