NetBSD/amiga should be able to run SunOS binaries so you might find doing that on WinUAE (download a pre-installed NertBSD HDF) easier than figuring out Sun emulation. I didn't try that yet.
Edit: Seems it might not be quite that simple. From the
compat_sunos man page, if the SunOS executable you want to run isn't statically linked, you need to copy various libraries from a SunOS installation.