What is the best way to create an authentic weatherboard wall?
One option would be to use the relatively new bricks with masonry profile:



If you aren't aware, the reverse side of these bricks includes the horizontal lines but leaves out the vertical ones. This allows you to create something like this:



This solutions provides the advantage of less dense horizontal lines, but being that this is a newer part, it also really limits your color selection.

Your pictures make it look like you are trying to build a white house, which is currently impossible using this part as it isn't available in white. The best that you could do is light gray, which is what I used in my example.

There is a 1x4 version of this part that would make construction much easier and sturdier, but it's only available in medium dark flesh at the moment:



This construction also leaves you with a brick pattern on the inside of your wall. It doesn't sound like this is what you want. One solution would be to create a double wide wall, but that may not be feasible in your case.