When you Cheat with these Cheat Sites then really what is the point of playing?, you will know where the Trader and all Bosses are, you will know where the best Biomes are for iron etc .. this just defeats the object of the game Survival and Exploration.
The next thing you will do is come to the forums and start to brag how you beat the game in 25hours.

you can just build a deep hole/trench around your base, and the trolls basically can't reach it. maybe they throw some boulders, but you can put walls up. they literally cannot melee though if you build a trench around your base

if you only want to play creative just use ghost command or stopevent

only immune to raids if there is no valid place for them to spawn on the island

The answer is no, even a "meadows only island" can spawn troll and other raids when the conditions are met. However if the island is so small that there is no place to spawn anything OR you covered up the entire "red circle raid zone" with structures preventing spawning, the enemies won't actually spawn during a raid (that's what hazelrah explained on the post above).

Originally posted by GeoForce:

Looking at several randomly generated worlds using the 'Valheim World Generator' app, I see some having islands with only meadows biome on them.

If I build a base on one of these, will it be immune to attack by trolls and higher level MOBs during raids as they cannot spawn on island, and would have to cross water to get there?

just remove your crafting tables and the events stop, unless they patched that.