@Hitman , your thoughts ?
Firstly, I want to say nothing replaces the squat rack. I remember when I training for a show in Vegas, three months out and my gym for no reason whatsoever remove the squat rack. After my session I went straight to reception and told them that if they don't get that squat rack back, I will quit the gym, then write a complaint to head of the region, and then let my displeasure be known to everyone else. That rack was back in there within two days...
OK. No squat rack. The best alternatives that I recommend are the following, and these exercise have helped me ecth in a lot of detail into leg sweeps, as well add size.
Walking barbell lunges - Not the dummbell version, I am talking about putting a weighted bar on your back and walk lunging. The good thing about this movement is, to can very quickly change how you hit certain parts of your leg. If you do a deep lunge, you will activate your glutes, and the hamstring tie-ins, also the sweep seperation between the outer quard, otherwise known as your vastus lateralis and hamstrings will become very prominent. If you lunge shallow, there is more effect on your front of your quad, your rectus formoris, which helps make the thickens in the middle. Combine putting your foot straight out at front, to making the face 1 o'clock and 11 o'clock respectively - this will work the inner quad, the vastus medalius. Squeeze the glutes every time you get back to upright position, pause, and then take the next step.
Straight after, do the leg extension machine, using the blood that you have accumilated in your quads. Work in a pyramid, five working sets, increase the weight with each set, by try to maintain the same rep range. Then one dropset, go back in reverse, and reach failure.
Jefferson Squat - This is a very good exercise that addresses the issues of the out quad, as well as tightening the glutes. Place weight bar on the floor, and stand over the bar, feet on either side, at a 90 degree angle. Squat down and grab the bar, one hand will be in front of your body, one behind, stand up and lift the weight in the process. Squeeze your quads and glutes at the top. Do a set of 8 reps, this is a very good exercise. Once this is done, straight into stiff legged dead lifts, and work those hamstrings, which should be saturated in blood, but use a lighther weight and work on the contraction at the top.
Finally, a modified hack squat. Place a barbell bell into the corner of the gym, stack the side facing out with weight. Now, using both hands, lift the bar up, turn around, and rest it onto your shoulder. You should be at an angle, due to the fact the bar is coming out of the corner. Now deep squat, if you keep your legs together, you will target the out sweep, but if you take on a sumo position, you will target the inner leg, and great for glute development.
Nothing replaces the squat, but I hope my alternative suggestions can give you something to work with.