Looking for fix: Chosokabe's crippled trade route

I have searched on the internet and this bug/feature has been reported by many. The game only allows a trade route to be established if your capital province has a LAND route connection to your subject of trading, such as a province with a Trading Port. SEA route connection does not count.

Then there is a big problem for Chosokabe, because its capital (Tosa) is connected to 4 provinces at max with land route. Even if you as Chosokabe own the western half of Japan and have 20 trading ports, the only provinces that you can trade from are the three sea-port provinces on Shigoku, the starting island.

Now this wouldn't make any sense. You have full control of half of the Japan and all the sea routes, but you can't ship things from the main island to your capital?

I can think of a few ways to fix this design oversight:

(1) Change the rule: You can trade from provinces that has a Sea route connection to your capital. This makes sense, too. An enemy can break those sea routes by blockage the port.

(2) Edit the campaign map so Awaji has a land route connection to Settsu. This is reasonable, too, as the Awaji island is very close to the main island.

(3) Enable the moving of the capital, so Chosokabe can choose to move its capital to another province that is part of the rest of Japan. This does not really solve the oversight, as any player who holds any provinces on the Shigoku island is still unable to use their ports to trade.

Can anyone suggest any mod or any starting point of how to make a mod for any of the above? Thanks very much.

yeah, i noticed this too. that's really annoying and pretty unrealistic, cause since it is part of your lands, you should be able to trade through its ports. but i've noticed this in napoleon and empire too. i don't know how you can fix this, i just hope they fixed it in FotS.

Another annoying bug is when you start conquering provinces and your main trading port gets moved to the front lines. I lost my entire trade income to a blockade that way. The latest one happened when I was playing one of the Fujiwara clans in Rise of the Samurai. After conquering Musashi, my main trade route got moved from Echigo to Musashi. When the AI blockaded that port, I lost all my trade income until I lifted the blockade.

I've noticed this as well. I doubt solution (1) and (3) can be achieved through modding, though. These are design features, and likely to be hardcoded. (2) may be possible, but I am not modder. I hope the developers will fix this.