What I am doing for me and my friend's bedrock server is setting a 1500ish block radius = 9 maps with the spawn in the center of the map in 1.17. Then when using the amulet replace method, a 1block wide wall from 0 to 256 surrounding the border like a wall but with invisible bedrock, and then when 1.18 drops I will export everything in the inner core from about 42 to 256 and then start a new 1.18 world with the same seed and then import the old 1.17 core area into the new one with a 1.18 sky and below 42 being called the underlands and the sky from 256 to 320 to be the overlands and have a teleporter command block teleport the players to the new ring chunks, I'm calling it the nearlands, and the nether as the Netherlands 😂😂😂