I know it's not GPD yet (I do the last day of the month), but I wanted to go ahead and share some more decorating ideas that we have used in the past.
Last year we made our own tombstones. Just like anything, it was a learning process. My wonderful husband made some tombstones out of plywood. We spray painted them gray and then I used black paint to write epitaphs on them with a paint brush. I highly recommend researching some funny and witty epitaphs and sketch out your writing before putting the paint on the tombstone. I’m sad to say, mine looked awful. I will probably paint over them this year and redo the epitaphs to make them more eye-catching. Maybe add in some dripping red paint to look like blood.
You could also use heavy cardboard to make your tombstones and just paint them gray or black. You could stick some fake limbs in the ground in front of them to make it look like the skeleton is trying to come up or wasn't buried all the way. You could also put spiderweb in between the tombstones to make it look really old.