Advice about drugs and consensual raping my girlfriend

I hope no one minds that I posted this question in a few other sections of Reddit, but there were some great initial responses and I was hoping for more detailed information. It sounds like the drug that might be best suited for what we are looking for is ghb (which I've never done previously). Some indicated Ketamine might be best. Below is my reposted question and a few specific follow-up questions. I am VERY grateful to anyone taking the time to help guide me with this. THANK YOU! Here's my ORIGINAL post/question.

"My girlfriend and I love many varieties of D/s kink. We love sex on MDMA because of how open it makes her. But most especially she (we) want her to be so completely stoned and wasted that she has absolutely no possible way that she could resist whatever I decide to do to her. She must remain aware and able to participate, but know that she is helpless. This state of helplessness should give her permission to enjoy the most kinky sex imaginable because she had no choice other than to experience it. Again I'm stressing that this is 100% consensual on her part and something we both very much want ... but are unsure what drug is the best choice.

Any suggestions as to what might best induce such a state? Please, I am hoping for honest advice. Thanks in advance."

Here are some additional questions ...

a) if you suggest ghb or ketamine, what is the best dose that is safe - but will still get her into the state we are looking for?

b) I heard that GHL might be easier to come by than GHB. True? Will it be as effective? Dosage for GHL?

c) anyone with experience in this area of wonderfully hot sexual perversion (yay) do you think two drugs combined will give a better experience? Dosages if mixed?

I'll be happy to share the details about what happened from this encounter. This is going to involve three people, and my girlfriend is hotly anticipating what will happen ... the helpless state from the drugs should strip away any remaining inhibitions since she is relinquishing all control.

Once again THANK YOU to everyone taking the time to reply.