Aww, Shew! Foot problems, like all the other chorus of parts, are so tricky! Is your RA flaring up in any other way or is your foot the only thing acting up right now?

It's risky to change anything so close to your ride. But maybe a thicker shoe insert with the bunion part cut out so it can have more space? I know you can't avoid puting pressure on that part of your foot, though!