You could merge double walls very low and then use short stone pillars as the wood blocks they are staked to.
Oh, oh! You should have the tracks elevated and going off the edge of your map or something. They could be used as a vantage point.
you can do about 6 walls length of tracks, if you put fake trains on the track and tunnels, you could probablly do across the crypt fully, that would be awesome in a new mombasa: im not a great forger, but to make tracks i use:
it was really only a test map tbh but i might expand it if i feel like it, geomerge the ends into the ground via tunnels and build something new around it.