The luff rope is a structural part of most beachcat sails I have seen. Unless the bolt rope is there to take downhaul loads, you will need some really heavy duty luff reinforcement. Probably some special 10.000 denier spectra tape or similar.
What usually happens is that the cloth in the luff stretches until a certain point when downhaul is applied. From that point on, the luff rope will take all additional load from the downhaul when you increase tension. This can vary between sailmakers of course, but I would be leery of a beachcat sail buildt in a different manner considering our 16:1 downhaul loads. The downhaul loads, bending our masts, are huge.
If the luff rope did not take any structural loads, what would the point be in installing the luff rope in such a manner that you have to apply at least some downhaul before the sail sets well?

I am not a pro tough, so if anybody know better, please enlighten me.

Replacing a luff rope is not much work at all. I am pretty certain I would need just an hour or two at home. A professional sailmaker in his workshop should be able to do it faster. It is a simple and quick process, but you need some beachcat experience to get the amount of "pre-tension" in the luff rope right when you sew the rope to the sail at the foot.