"I don't really care about my squat"
Then you are missing out on one of, if not the, best exercises.
You obviously cant handle deadlifting twice in a week, deadlifting is a very taxing exercise for your body. It can take even some of the greats weeks to get over a brutal session.
You say you are doing a speed day but then say you are deadlifting heavy twice a week.
Are you deadlifting three times a week in reality?
I think the exact depth for SLDL depends really, arm length, leg length etc. I would say get a good stretch in the hammies without hitting the floor.
As for how much to use for them? Depends how much you can handle but if you are already deadlifting 3 times a week I would, if I did them at all, do them light for reps.
No offence but with a 130kg deadlift you arnt very strong yet. I would stick to the real 5/3/1 plan and use zercher squats, goblet squats etc in place of the back squats.
Then find a new gym with a squat rack.
"don't have a squat rack" =! "great gym"
I have a free gym but pay for a gym with a squat rack.