Alternative to barbell back squat

I don't have a rack or a stand, therefore I cannot do heavy back squats. The highest I can bring up the barbell is on the seat of a pair of wooden chairs.

Here are some alternatives that are more reasonable and get more out of less weights.

Zercher squat: Make sure to put some type of padding around the bar to reduce stress on your elbows. This doesn't require the flexibility of a front squat. But it still hits the core like crazy.

Zercher squat of block/chair: This one is easier on the recovery and can develop a bit more explosive power.

Front squat: Simply do some type of clean so you can rack the bar on your shoulder. This requires flexibility that I right now don't have to a great extent.

Behind the back deadlift: I find this to be a decent exercise to hit the legs, especially quads. It is a pull of the floor without much of the stress on the lower back as the deadlift.

(Reverse) Lunges: Although you carry the bar on your back, it will not be a lot. Even if you are strong where the weight gets high, you can do zercher lunges. You get more out of less weight. This is one of the exercise I use (barbell on back for now) with much less weight and I get a good leg workout from it.

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Image sources:

https://www.skimble.com/exercises/37136-barbell-reverse-lunges-how-to-do-exercise
https://industrialstrengthgym.com/2019/06/03/zercher-squat/
https://www.stack.com/a/front-squat