That's awesome! i did design and print a rear bento box for my propel a couple of years ago. it worked great until it disintegrated in a flat second. My advice: carbon fiber cloth or (cheaper) fiberglass cloth to reinforce everything (or pre preg to make your life easier, presumably). My box failed in the middle at some random layer line, which retrospectively, makes sense. It was more of an experiment than anything, i was phasing out the use of that bike already, so i didn't print a new one and didn't get around ordering cloth.
i like the ghetto TT front end rig a lot, well done!