I've never really been happy with my old tombstones because I've always had a hard time keeping them standing up straight when they are placed in the ground.
In the past I've used either wooden or rebar stakes, but they look like crap from behind or snap if there's a big gust of wind.
This year I purchased 2"x 6" wood lumber, I cut the wood to match each tombstone to size, drilled holes into both the wood and tombstone, placed 8" spiked nails filled with construction adhesive foam board into the tombstones. I then drilled two additional holes on each side of the wood to pound nails threw into the ground and painted the wood grey to match the tombstones.
Next year I plan on making many of my own custom tombstones.