Back and legs are two of hardest body parts to train intensely and effectively on there own, and you want to do them both in the same day?
It def can be done but my question would be why?
Wouldn't do it,Legs are a day for themselves... You want all your blood flowing through them as you tax them out on training...Only body part you want to train by itself, biggest muscle on your body also...If your training anything else on Leg day,your taking a lot away from maximum gains on legs...
It's absolutely fine if you can put full effort forth for both excersises, but that's not likely. Imo put dl with back, and do legs separate, that way you have more energy and strength to hit both just as hard
Blood flow would be the biggest issues. Legs will sustain a massive pump and draw large volumes of blood into them as you tear them down during a workout. I would think it weaken your results from both groups some. And as someone else said? Why? Just do legs on their own day.