I think the best way to practice will be to do it just as we do it here.  Even if you don't start moving the carriage much at first or even at all, just getting from sitting to standing in the pike shape can be an exercise in itself.  Also, as you start to move the carriage, stay close in so that if you feel that you are losing control the bar is there to sit on.  

I agree that the lunge with no hands is certainly a challenge that takes courage but don't feel shy to keep you hands down on the bar until you feel ready...you could also have a pole nearby to help you balance when you do decide to go for it.

Thank you for taking class with me and it would be wonderful to see you again in Santa Barbara.  Remember, the advanced level is a goal that can take years of practice so go easy on yourself and most importantly, take care.