Ah ok. I feel like a big wall would make the spawn ugly.. Just make holograms saying &4Do NOT walk off spawn, you will die and lose everything. &4Land is protected around spawn, which means you cannot mine blocks for ____ Blocks out. The best thing is just the holograms and if they still do it, then it's on them.
How? With that and the holograms, they would know to do /home instead of trying to mine blocks they can't
Running into invisible blocks could cause issues such as... "Why can't I leave spawn?" "Is this broken?" If what you say is true about people not reading the stuff, I am sure the hologram being there won't help 100% of the people who join.
Well i think it's better than having a big wall. I know when I join a gamemode I read the holograms, and I know when people don't know what to do they go to spawn and read all signs and holograms.