Fantastic build along Shaun.
Did you consider just gluing the bottom limb to the steel sleeve?
That's how the sleeves I used years ago worked, using just one brass sleeve.
Gives you an extra brass sleeve, which I'd be trying to conjure a use for. Would be tempted towards two upper limbs, but then I never could answer the question of... why.
One of the things I noticed about mine was it would swell and shrink w/ the humidity. In fact after a couple of years it was getting loose so I shimmed it with JB Weld. I may not have had the wood completely seasoned when I started, or this may be fairly common. I have a sleeved takedown glass bow that has gotten loose over the years as well, but two shims of butcher paper will keep it tight enough for now.
Sleeved bows are simple and convenient, add just the right amount of weight in just the right place, but it does take a little to get used to the shape. Easy enough to build one up and shape it, although I have grown to like mine just like they are.
Great project. Inspiring. Thanks for posting.