There is still a big Milford fleet. I happened to see a big Milford trawler today in Mallaig. The crew all spoke Spannish but that's because a certain labour government did not take a stand about the common fisheries policy and allowed the flagship rulling to go ahead. One should ask the question why Spannish owned Milford trawlers can make a living while Welsh owned ones cannot.
As for your twin net theory, I think you under estimate the integrity of our british fishery protection officers. Do you think that the French can haul, stow and re-set another net faster than it takes the "bobbies" can reach a boat. The FO's also have the authority to search a boat. A net is a hard thing to hide in a hurry.

One more thing! Lobsters live in rocky ground and trawlers and beamers avoid this terain as much as possible. You cannot tow a beam or a trawl through a rocky bottom otherwise you would damage your nets even more that of catching a fleet of creels in it.

You should get over to Brittanny more often. They are really nice people and many of them can even understand Welsh!