I have just recentley set a line in the same fasion over on the west coast, Ross.
Sadley we had to leave the beach as the tide was comeing in and pulled it in early,
I will be doing it again and giveing it a bit more of a soak next time.
I used a sack at each end with a few rocks in, and a 2 or 3ml thick cord as a main line to the beach, tied it off to a well dug in rod stand.
Crabs were a problem, so I like the float idea and maybe Ill try just weighting one end next time.
Trial and error…but the genral idea has merrit I think,
Be keen to hear how ya all get on with your next attemts.