I’ve been using Traefik for past year as RouterOS container and that works well for me. This thread (despite the title) covers both Traefik and NGNIX proxy manager:
http://forum.mikrotik.com/t/container-traefik-on-rb5009/165849/1
Specific to NgnixProxyManager, see:
i.e. Setup container loosely following Mikrotik Help, and replace “env” and “mount” with details from https://hub.docker.com/r/jc21/nginx-proxy-manager, then follow NgnixProxyManager’s guide to set it up as a proxy.
Regardless of what you use…the real trick is mapping the ports through the firewall via the VETH as often the harder part than installing, since the rules can get tricky (i.e. input vs forward, src-nat vs dst-nat).