Cheers, Chris.
Yes, the Cave 1 is a tough unit. This is repetition of something I mentioned in another thread, but there is nothing which can break. The pegs might pull, but that's it. It's problem though, is the flapping. It is noisy in a rough wind.
I think beaks are a good idea for Britain, otherwise tarps can behave like those suction pumps Science teachers use. You know the ones that fit on taps. The falling water draws air through a tube at right angles. The back end of my Spinnsolo behaves like that so there is almost always a draft coming in through the funnel-shaped front. If I could sew, I'd add beaks to make it look like Jay Ham's MYOG tarp. A tarp with a catenary cut to reduce flapping, beaks preventing the suction effect and spinnaker fabric's reluctance to absorb condensation could be spot on for our hills.
And a Serenity Shelter to keep out midges and prying eyes. Except, it would then be a tent, not a tarp.
Best wishes.