G_STRNG; been there, done that, still suffering!
I'm also what is termed 'underweight' for the R22, (and like yourself, not very tall) - every time I fly it, I take a specially constructed bag of weights with me. (Although will be having second thoughts after having the collapsable seat scenario re-iterated in this thread - weights and bum...ugh).
When I started, I use to use a cushion, (as mentioned in this thread), but couldn't get on with that at all - the rear cyclic movements didn't feel right, and I felt as if I had less control.
Besides, it was getting silly; everytime I wanted to fly solo, it felt like I was taking half the contents of either the car or the office with me! Once, I had to run back to the airport because I'd forgotten to remove the weights, and the next person to fly was a rather large guy...
Whirly - love the idea of the water containers, how come you've never mentioned that one to me before? (Then again, can't remember if I've told you of my underweight problems flying the R22).
G_STRING, it does get better as you get more practice, but keep it up. As mentioned on another thread, helicopter flying is a perishable skill, which will quickly deteriorate if you don't use it. I found this out after finally getting back solo in the R22 a few days ago, and being surprised by how I 'jumped' into the air, (even though I was expecting it).
Did settle down and enjoyed it though.
Have fun
ariel