Margarita. There is a specially made cushion that is made to go between the guitar and your leg to lift it up to give the same effect of putting your your leg on something. It is supposed to be better for your back than elevating one leg.

Being what was so delicately described as "fat" myself, I have always had trouble playing a guitar of normal depth. Then one day I saw a video of Bukka White. He held his national at 45 degrees (he was fat too). I tried it and it is a great position. Besides the acoustic advantages that Rick mentions, it also is a more stable way to hold the instrument. It just rests there even if you take off the pressure from your right arm. It is much easier to slide up and down the neck--at least for me. Holding it in the "western" way (waist on right thigh), I always felt that it would get away from me when I moved down the neck with all the strings unfretted. (Is there any way to describe guitar playing without double entente?)

Murray