I found a few whales with millions & millions of resources.
I went in with rocket buggies & maxed out my storage every attack.
Had to upgrade repeatedly but the upgrades happened in seconds.
There were three. One was named "War" another was "Jzzbo" (?) and another was something like funnybase or something like that. Check all the high level bases & it doesn't matter your level you can attack.
The resources are not protected.
Hit them hard then skip sectors as the owners will attack you.
What's needed is a "friend" in that sector to invite you.
Here are the coordinates: Sector 378 12,183 the others are in the area.