Hi Jenny,
Over the years there has been several discussions on the brown rice diet here on this forum and on other mb discussion groups.
And as always, different conclusions - some have fared well with it, some find it too powerful, and prefer just keeping a more balanced mb way of eating.
The bible for all you want to know is in the following book, which you can order at the shop here - but there's also a great deal of info written up - take a look:
"#7 Diet, An Accompaniment to Ohsawa’s Zen Macrobiotics"
I think it's super exciting that you have a farm. My most favorite food to eat is for me when I go out and harvest my own kale, just enough for what I'm going to eat almost immediately after harvesting it. I also have dreams of one day growing much more of what I eat - it takes me a while to keep after my dreams, but I don't give up.
Another reason I love mb - I can keep working at it all my life!!!!! always where to improve and change.
as for sweets, try going in the direction of more sweet vegetables, of softer foods (sweets are yin, so are softer foods - but don't make all soft, keep variety), less salty, baked, processed (like soy milk, etc) foods which may cause you to desire the sweets, and even vegetable kind of desserts, like with sweet pumpkins, carrots, sweet potatoes - if you must have sweets, my first preference would be with amasake, as it's grain based and fermented.
if you still consider going on the rice diet, at least try to find someone professional in the mb world who can guide you - remember, it is considered an extreme diet, and must be done with caution and only a short while (a week to 10 days I understand).
Klara