If you cut oak and beech branches now, and zip tie them all over the stand and on other branches, they will hold their leaves.
Otherwise, lower or raise your stand to find good background cover, find another tree or think about hunting on the ground.
Being 10' up with super background cover is WAY better than being 20' up with no background cover and looking like a giant bear up a telephone pole. While wind direction is critical, also always place your treestand according to the background cover, shot angle/shot radius and how the sun will shine on you, and when.