I've posted these before, but I can't find the message. I have a Kindle 1 and like you, prefer to hold the book reader in my left hand so I can be doing something else (like eating) with my dominant hand. Here's my usual holding position & the slight move to tap the "Next Page" button.
The biggest change came with reading in bed because I was used to laying on my left side & holding the book over the top with my left hand, reaching over with the right hand to turn the page. It took a while, but I finally worked out a comfortable alternative for the eBook reader.