The front awning leg is down in this pic and the back leg is still attached to the Expanda this is how I usually set up, having them down doesn't make the awning unstable as such but it does make it weaker in high winds.
Be sure to put a peg and rope at each end of the awning barrel as in this pic and if you want you can also drive a peg through the foot of the awning arm(s) that are off the van.
I used to do this but I no longer do because if I need to get the awning in in a hurry (big storm coming) its another peg to deal with, with the two ropes around the barrel, four occy straps on the long wall, three on the rear wall all holding the awning down its pretty dam secure.
We have been through a couple of decent storms set up like this and nothing has moved

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