For the headstones I have made some bases in the same way I made them for the paper minis, just adjusted the length and slot position. And if you want a little enclosure around it I made another part just for that.
Once I have built a couple of graves I put them on a test grid and I think they look quite nice. Have to build some more for my large map
If you don't want the thin headstones but double them up to give them some mass, then I also made an adjusted base version for them as seen in the last pic.
Next I am going to work on the mausoleum/crypt entrance building. And continue to build my army of graves!