ok the problem with wind and tarps, (the umbrella idea was a joke!)
camp low and keep it tight is your obvious and sensible option, i have used a poncho/tarp/basha for about 20 years and they do have some limitations, high wind is one of them.
on my sca-fell trip though my tarp flapped like a flag in very strong wind,it kept me dry and warm, people i was with said their tent actually lifted off the ground overnight, that impressed me!
for mountain conditions tarps aren't great as you discribe, bungees can be usefull here , they have a bit of give (stretch) allowing the tarp to move slightly reducing stress on the attatchment points.
you could sleep on one long edge of your tarp for added protection against horizontal rain.
in really high wind run a couple of cords over the back of your tarp to keep it on the ground!
peg down your bivibag/mat with a bungee to stop them flying away!
if you have time build a small wall to stop wind, on a mountain course one of my mates built a "U" shaped wall and put his tarp on it as a flat roof they had a very dry comfortable night everyone else with bivibags got soaking wet, just by getting in and out of their bags!
so in conclusion i would suggest
low profile.
add some structure to the tarp
take spare cord
but above all know it's limitations it is after all just a waterproof sheet!
top marks for tarp camping in the alps ! :You_Rock_
camp low and keep it tight is your obvious and sensible option, i have used a poncho/tarp/basha for about 20 years and they do have some limitations, high wind is one of them.
on my sca-fell trip though my tarp flapped like a flag in very strong wind,it kept me dry and warm, people i was with said their tent actually lifted off the ground overnight, that impressed me!
for mountain conditions tarps aren't great as you discribe, bungees can be usefull here , they have a bit of give (stretch) allowing the tarp to move slightly reducing stress on the attatchment points.
you could sleep on one long edge of your tarp for added protection against horizontal rain.
in really high wind run a couple of cords over the back of your tarp to keep it on the ground!
peg down your bivibag/mat with a bungee to stop them flying away!
if you have time build a small wall to stop wind, on a mountain course one of my mates built a "U" shaped wall and put his tarp on it as a flat roof they had a very dry comfortable night everyone else with bivibags got soaking wet, just by getting in and out of their bags!
so in conclusion i would suggest
low profile.
add some structure to the tarp
take spare cord
but above all know it's limitations it is after all just a waterproof sheet!
top marks for tarp camping in the alps ! :You_Rock_