You should see if any of these fits your needs:
https://wiki.archlinux.org/index.php/Wayland#Window_managers...
I too have been longing for an Openbox port for Wayland but have sticked to Sway in the meanwhile.
I've never heard of EvilWM until your comment. I'd be curious to test it out, but wondered if there are any more screenshots of it. (This one is just not enough to judge: http://www.6809.org.uk/evilwm/images/cap1.jpg )
Evilwm still seems like the window manager that got thing mostly right to me. It draws the windows and there's a keyboard short cut for opening an Xterm (and for moving and resizing the windows), you don't really need much more than that. Sadly it seem that the focus for the simplest window managers is tiling, which I also to like.
Hopefully a non-tiling, dead simple window manager for Wayland will appear in the future.