That looks like a fine nice transportation mod…..

I will surly try this out in my next base (or maybe just add it to the exiting)

I find it could be a nice small amount transportation mod, just a little slower and takes up not much space….

I see the problem with the 2x2 size of the rail. I sincercly hope you can slash it down to real 1x1 size, but its obviously some trouble, sizing all trailing things (signals/stations/pumps)
How about a special track with a 2x2 size but 2 lanes (one fro one vice versa) and have a small turntable or special turn-circle.
Maybe there is the possibility to have a line changer rail-part to connect the from you mentioned problem of the then 4 separated rail networks when moving t 1x1 size ?

I my mind I would use this mod as a small scale transport between belts and trains, because currently I have such a situation to need to transport small amounts of items between far away bases, where a train is just too much and belts have the problem of either laying down a track and sorting all items out and running a red wire all a long to keep the belt from chocking on single items. With trains you can limit a cargo hold full of different items and transport it

Rails unfortunately have very little modding functionality.
They are hardcoded to be 2x2. There is nothing I can do to change that.

There are multiple problem with having 2 1 width lane rails.
Trains on them will share the same block
A left and right lane won't be able to be part of the same track (a train on the right lane can't switch to the other, no matter how complicated you make your rails). You are effectively making 4 different tracks.
* Curves are weird. If you look at the curves now you'll see that trains will switch from driving left on the 2x2 block to driving right on the 2x2 block. This is because on a horizontal track they are on top of the 2x2 block, and on the vertical track they are to the right. Doesn't matter what direction the train is facing.

What I have experienced with is adding the placeable-off-grid flag to rails. Then you are able to just snap it to 1x1 tiles instead of 2x2 tiles. Problem then is that you can't place any stations and signals on those. And again you'll make 4 distinct rail systems that you can't connect.

i would rather a 1x1 rail system that never connects to other size systems. it is a shame that stations/signals can't be modded for 1x1, perhaps a request for the factorio devs is in order. have you asked?