Coming from a somewhat large company, there are many ways small companies have made huge thorns in our side. There is many strategies for them to stay alive important loot intact but the simple big fort and surround it option mega tribes do is not the way to do it for EVERYONE. Small companies have more freedom in that sense I think, multiple outposts and shared islands, build hidden, out of sight, multiple outposts again.
Lastly, if you want it simple just find a big tribe to take you on their island, they should protect it and you if they are decent.