Until you get your ganzo weights for squats, try one and one-half squats. Here's how you do them
Squat deep (the deeper you go, the more you engage your glute muscles - but only if your knees will handle it). Raise up halfway, now go back down. Raise up all the way.
Also, reverse lunges are good. If you get that back foot way back and put your front foot on a step, you'll get a nice workout. Keep switching between legs & you'll get a bit of an aerobic workout as well.