You see the trick here is to not over invest in one base.
Typically what I do is look for a swamp with crypts near a black forest and make an outpost to refine the iron there. This will cut down the sailing back part.

Tough luck on your crypt search though. Hard to think of having a huge swamp with no crypts. Setting up on a copper node near the shore of a black forest will easily get you the materials you need for the forge and you can make what you need there.

Personally I am on a seed where finding silver was rough. Had to look around for a while for a black forest near a large mountain... now my problem is getting enough iron there to upgrade the forge and make a silver sword.

I've also had games/seeds where I never found the trader and had to live with the reduced carry weight. That was a bit rough, but I was able to manage.