While messing around with the '87 release of GCC, I was going through the steps of setting up TME, and I stumbled across this derived emulator that is incredibly simple to setup and run, unlike TME:
https://github.com/lisper/emulator-sun-2

Additional patches adding a BPF backend Ethernet adapter is here:

https://github.com/sigurbjornl
The program itself is only slightly C++ with a few variables being declared inline which was trivial to move to section starting to get it to compile with a picky C compiler (Microsoft C). The IO is SDL based, so making an x86/ARM win32 was really trivial. 
Anyway for all the SunOS enthusiasts I figured that you would love to give this one a shot! 
For Windows users, or anyone wanting to just run it on some unsuspecting normies I put Win32 x86 binaries here:
https://sourceforge.net/projects/bsd42/files/4BSD%20under%20Windows/v0.4/SUN2.zip/download
I have to wonder how impossible it would be to integrate it into SIMH...