Gotcha. That is the standard travler track for the hobie16 (and many others). Your friend has the right idea, in close when upwind, traveled out for downwind. This is basically the same on the main sail...

That took me years to remember and even more to understand why.

A self tacking jib is a unique and modern curved track that allows the jib to switch sides on its own.... different creature...

I dont know how nacra 5.0's have the jib blocks but to reconfigure them is relatively big undertaking... I don’t know what would happen if you put travler tracks on your beams but I am sure that would change the angle of the jib block / sheet and move the pocket / effect the jib.

I think working out a bungee system is the way to go. Either from the bridal as i show, or from the outer beams - to the mast- to the other beam in a piramid shape (as I did on my hobie 18).

I had a eye strap on each side of my beam and 1 on my mast that I would run a bugie through each time I rigged.

Below is a pic of how I ran it (in red)