Interesting. Wouldn't it be hangar bays and not anchorages which were needed, though, or am I misunderstanding how trade works? Since anchorages raise the fleet limit, whereas hangar bays protect 10 more trade a piece.
Though I'm not 100% certain how it is you suggest setting up a trade network.
Sorry I wasn't more clear. So, bastions provide trade protection in systems that *don't* have an upgraded starbase. As you mentioned, hangar bays provide 10, so with x6 hanger bays, a bastion will provide 60 trade protection (as I'm sure you know.) This, however, is not the optimal way to ensure 100% trade collection, and should really only be used to protect the minor incidental trade from outlying rural worlds. The key to trade collection lies in the fact that systems *with* an upgraded starbase (of any kind) cannot generate piracy---they are immune.
So, imagine seven systems connected in a line by hyperlanes: 1-----2-----3-----4-----5-----6-----7
If 1 is your trade capital, and you build anchorages on 2, 3, 4, 5, & 6, and then make 7 is a trade hub with full/six trade modules, then every system within six jumps of starbase #7 will be collected by 7 and transferred down the line of piracy immune systems to the trade capital. I find that 1-3 trade hubs is all I need to collect from 20+ worlds until I am able to get gateway technology. By placing trade hubs 12 jumps apart, connected by contiguous starbases, 14 starbases can collect trade from a huge area of a space with 100% efficiency and 0 piracy.
This is what I meant by a central "backbone" of stations. The intermediary starbases between the trade capital and trade hubs can be anything, but having multiple trade stations with overlapping collection ranges is inefficient and doesn't seem worth the 12 trade that could be generated from modules compared to the 36 naval capacity, so I always them into anchorages. Sometimes I will leave my trade capital as a trade hub, sometimes not. It totally depends on where the planets are and how I can get the best collection coverage from as few trade hubs as possible.
It used to make sense to build starbases over planets, however, that is generally a terrible idea in 2.2.x. Instead, you want to build a trade hub where it should be once it has a reach of 6 to collect from as many planets as possible. And then build bases/anchorages in an unbroken line from trade hubs to your trade capital. So long as all trade is moving from collection hub through systems with starbases, no piracy will ever be generated. Bastions can be built for purely defensive positioning, and no patrols are necessary.
This strategy does mean that some large, "key" worlds may not be in collection range during early game, so building bases in the manner I've described is a strategic choice that will result in less trade collection during early game. I prefer to build my bases where I want them long-term, and I simply don't build up trade on worlds until it can be collected. This often results in generator districts during early game (that provide more energy faster from fewer pops), that I then turn into city districts mid/late game, once the planet's infrastructure (gene clinic, cloning banks, robotics factory, etc.) are in place, and I have the collection range to take advantage of clerk generated trade. Changing districts is much cheaper, as well, costing minerals rather than the alloys needed to relocate or restructure a star base.
Let me know if any part of that is still unclear. No one should suffer pirates needlessly XD