Hi Orchid,
I think you could provide the massage sitting. As long as you are positioned higher than your client, so you can use your body weight throughout the massage - this is very important, as if you are on the same level you will have to use a lot more physical strength, which may cause extra strain on your spine, not to mention your thumbs, wrists and chest. It's an interesting question, so please keep us updated on the solution you find. Good luck