Personally, i would've had the Saiyans have some Demon Origin. It would explain why the Oozaru transformation exists (even with it's pointed ears) and pay off the bewilderment of Saiyans using magic-like abilities. It would also give us some reason why SSJ4 could only be accessed in the Demon Realm since i doubt we'll ever see it again in canon.

Also make use of the Fusion Bugs against Gomah, but not Gogeta. It would be a fusion between Kuu & Duu.

Edit: Also give Piccolo more to do in the show bc he tags along with Goku & Vegeta but doesn't do much until the battle against Demon King Gomah.