Personally, I don't really play Rare Zelda games, but this is one amazing guide to the bosses of ZA. These pictures impress me as well (I didn't really know that Zelda's Adventure had such beautiful drawn backgrounds). I would definitely recommend making more Rare Zelda boss guides, but for more popular and easily accessible games. Zelda's Adventure and the other Philips CD-i games are rather hard to acquire, so I recommend making a boss guide (or any guide for that matter) for games like Master Quest (technically a Rare Zelda according to your list, but the boss battles may not be so different from the original OoT bosses). In that case, I would just suggest for you to use your expansive knowledge of Zeldas (both Main and Rare) and try to come up with more threads like these.
I don't make that many posts, because I never have anything to say. When I, the DARK MASTER, make a post, it must be perfect.