For bulk items you want a Snekja or a Knarr with a dock to teleport back to and it must have access to the ocean by either being on the shore or being on a river that can path into it. This means that deep inland, you are safer from bigger, stronger, scarier factions because transit and trade relies heavily on access to the high seas. Any river system not connected to the ocean means any Knarr or Snekja built on it cannot get to the ocean as far as I can tell so far.
Otherwise a rowboat with two chests is really the limit on thingwall transit, some trade stops have public beds of high quality that restore travel weariness faster. All of this means that goods must move along the open world more and spends time in areas where it can actually be stolen or gives bandits an option.
If you want to trade, take into account these river positions by planning accordingly on the
world map.
The better access to trade nodes you have the less safe you are, but the more rewarding it can be if trade is active. Generally it is worth the risk. Wagons can also use wagon stations to fast travel but require more setup arguably than getting your first Snekja does, as you need tamed animals.
There is a market utility
here which lists current trades and for what items or currency.
From my personal perspective, I've traded more after the travel changes than before, but that's probably due to having less valued items in the past and the lack of organized shops.