I have a pretty pronounced imbalance between my quads and my hammies/glutes. I have been able to work through most of the pistol squat progressions with little effort on the quad portions but I'm running into a wall on the glute ham raises. I work out in a standard office gym and so don't have access to a lot of useful equipment and I don't have a partner. What are some modifications I can make to the ham curls (since I know I need to roll back in that progression to something easier) that I can do without a partner? I'm doing leg curls at my body weight as an alternative for the time being.