Tourniquet was my method of choice if I didn't have access to N or SN. I do have SN now, though I wouldn't combine it with the tourniquet method.
Tourniquet method, when done right, is quick. Only 2 items are needed: rope and a stick (a ruler would work, an Ikea bed slat for example…that's what I would likely use if I didn't have SN). The issue/worry I have with the tourniquet method is unconscious flailing. Then the tourniquet may become loose and all goes to shit.
If I were to use the Tourniquet method, I'd not take SN prior. I'd likely take a benzodiazepine and/or get high (ganj).