Will this Leg Workout be Too Much for my Lower Back?

Hi guys, at the moment i’m trying to put some weight on and have just finished 4 weeks of doing the 25 method by Waterbury. I feel now is the time to change routines, so i decided to design my own workouts based on thib’s workout design article. Everything seems okay, aside from my quads/hams workout, which i am worried will place too much fatigue on my lower back. Here’s the workout i came up with:

A1. DB LUNGES
3 x 6-8
60 sec. rest

A2. DB ROMANIAN DEADLIFT
3 x 6-8
60 sec. rest

B1. DB SPLIT SQUATS
3 x 8-10
45 sec. rest

B2. BODYWEIGHT LEG CURLS (like a 3/4 ROM glute-ham raise)
3 x 8-10
45 sec. rest

C1. DB STEP UPS
3 x 10-12
30 sec. rest

C2. SWISS BALL LEG CURLS
3 x 10-12
30 sec. rest

So first thing you should notice when critiquing this is that all the exercises are either bodyweight or dumbbells as i workout at home, so no leg curl/extension machines/barbells. So basically i’m wondering what you guys think, does it seem okay? Are there any substitutions i could make? Keep in mind that when i designed this i tried to stick to the recommendations within the article.

You have one exercise that places some stress on your lower back. How could that be too much?

i don’t know, maybe i’m just being paranoid, thinking the lunges/squats/step ups would fatigue the lower back on top of the deadlifts.