Substitution for excersizes due to equipment

[dcairns1]

I soon will be switching to the F5 U/L program but I am unable to do a few leg exercises due to a lack of certain machines and I was wondering what good alternatives would be for them.

These exercises are weighted back extentions, leg press, and leg extentions.

For leg press I could do front squats but idk if that is ideal right after back squatting and doing some form of lower back work.
For leg extentions I could do step ups possibly?
Also could I do rear foot elevated split squats instead of lunges possibly?
Thank you

[SuffolkPunch]

Leg press -> behind the leg barbell hack squat. Be sure to keep your torso as upright as possible. If the bar hits your legs, it's because you are leaning forward.

Leg extension -> sissy squat