Tip for Beginner Traders: Trade Agreements and trading nodes

Do you find out that the AIs are less and less likely to trade with you?
The tutorial tells you to give them 1000 koku first. This is ridiculous!

AIs are less happily to trade with you once you start occupying the six trading nodes on the sea.
All you have to do is, immediately before negotiating for a trade agreement, manually move your trading fleet slightly away from the trading nodes.
The AI is tricked to think that you have 0 trade nodes, and will be very happy to trade with you. You can even ask them to pay some koku for this privilege.
After the deals are reached, move those fleet back to the trade nodes. Buhahaha.

This tip and payments for military access are the only way I can survive at Legendary.

It seems that in your Shimazu AAR, clans are willing to pay more if you own the trade nodes.
I assume this is when they need those goods to produce the higher quality units.