I haven't tried the church camp spot or the courthouse for that matter. But my favorite spot is the top the saloon. The L shaped hallway that has a drop off into the saloon at the end is my personal favorite spot for two reason. One, only one door and window that zombies come through, and both are at the end of the hall. Second, if you are getting overrun, you can escape by dropping down into the saloon out the back. Having that escape route is nice. Made it to 41 solo in that spot before the guns just wouldn't keep up.
As for the permanent tombstone, It is a theory but it did work for a friend of mine. Buy 4 perks prior to round 4. So use the bank and buy them up. I am betting it works. The 4 available are Mule, Jugg, Speed, and Quick. You can unlock to Scavenger too if you like. My friend bought Quick, Scavenger, Jugg, and speed.
So it may not be official, but it did work for him.