Hi Ricardoco,
Hmm, awkward.
I feel the onus has to be on the party being dragged up the beach.
I guess that the dragging line and hook is fairly strong, to cope
with various craft, some maybe quite large.
First off i would suggest that the attachment that you use to couple
to the dragging hook could be attached to your craft by a rope or
line that is only a little stronger than needed,
therefore any 'snag' or obstruction would hopefully disengage by
breaking the coupling to the hook, hopefully with minimal damage.
Also i would like to suggest some form of quick-release at the party
being dragged, again to hopefully prevent a 'snag' becoming a bigger
problem.
I am unclear as to how the dragging hook gets down to the craft to
drag it up the beach.
Maybe its some sort of loop ... ?
May i also suggest that any sort of signal to operate the proposed
lights, would be to sustain the 'Off' condition of the red light
when in use, so that a failure would bring up the red light.
I think a simple RF setup could be easily made. I don't think it
would need to be very powerful, i guess both ends have a supply
available. Reliability would be more important. The use of lights as
you describe sounds simple and effective to me.
Best of luck with your endeavours to save others from injury.
Regards, John