We have survide some horrendous winds when others have been destroyed, but i can tell you this was only through previous bad experiences. When we were kids our big frame tent was brought down, by some heavy winds, luckily we were staying on a farm with a blacksmith and he repaired the broken joints of our tent. My dad then went out and bought four screw in ground anchors and a couple of ratchet straps which we threw over the tent. Further tents were damaged that week but ours stayed up . When we had our own frame tent I always carried ground anchors and ratchet straps and on one occasion they came to the rescue when many tents were destroyed but ours despite being in one of the more exposed positions stayed firm.
We also had a lightweight but large tunnel type tent broken, despite everything being pegged down, this was as much to do with the accompanying rain as anything else, which meant pegs pulled out very easily, this was when I learnt about double pegging, and guying.
Having once again fixed the tent this time involving whipping tent pegs to broken poles with string, as splints, all guys were doubled up and double pegged, again our even already damaged tent survided whilst others continued to fail.I
t's amazing how strong even thin wire pegs are when double pegged( I usually use a second peg pegged across the peg holding the guy rope). I now carry all the pegs for all five of our tents in one bag(unless backpacking)that way I always have loads of spares. We always carry spare guyline on a roll and a few heavy duty stakes too.
Now as a matter of course every guyline is fully pegged when setting up the tent and as I said we always carry a large roll of 5mm paracord.
For the past two years we have had a helsport lavvu but yet to experience any really serious weather in it. but in preparation there are already extra guys tied to the upper guying points and everything is always double pegged.
whit regards to the double elastic rings I always peg through one or both depending on which allows me to fully drive in the peg.
As for Arisaig, sandy soils can be the hardest to peg out in, you may condsier using you bags filled with sand to weigh down your gylines od consider digging a hole, double pegging your guylines in it placing a rock over them and then burying the lot in sand again, you could try some snow stakes as these will work in sand too. Also flat type pegs with holes in can have wire pegs put through them and then buried to give better grip, it's all about improvisation and using what you have available at the time.