If you can't stake it properly, put in some 5 lb rocks.
Or, unless you plan to spend another night at Trail Camp, you could stow it in the morning, so it's ready to carry down in the afternoon. If there is any thunderstorm activity, though, it might be nice to store all your extra gear inside until you return. Just don't leave any food inside -- the marmots will chew through to get to it. In fact, leave it open a little, so they can get inside without chewing, regardless of having no food.