Maxi, are you aware the release date is the 18th and not the 11th, this was changed a few weeks ago.
I was going to suggest something similar. How would it be planned - is it worth marking out a large area in structure planner into 25x25 plots (or something similar)?I still think the only way spawn can be fair for everyone (old and new people) is that players are given an x by x size plot to build their spawn house on.
Another thing to add in if you go down some sort of route like that - i.e. people registering for a 'spawn house plot' - how about people registering to make a 'useful community building at spawn'. i.e. same size as the houses - but it will contain the nether portal in, or another one with a melon farm, or another with free stone tools for noobs etc.
Just an idea.
Can you add me to the Whitelist?