for safety reasons, it's probably always a good rule of thumb to avoid using any tinted shields when riding at night (even the yellow/amber ones!). that being said, i'm kind of in the same boat as you (except i have a biltwell gringo s helmet) i don't know if the bullitts offer a "gradient" shield, but the gringo's do and they've actually worked for me at night time. well, that is with a decently-lit street. the gringo's also come with these in their "bubble" visors as well. i like how it gradiates to clear towards the bottom, so you kind of get the best of both worlds. if i find myself struggling to see at night i can simply click up the visor a little bit and have my sight be more in the "clear" part without having too much wind blowing in my eyes, so i don't need the additional clear goggles.
i do think the best bet for you is just carrying around a clear pair of goggles/foam padded glasses that you wear with your visor up during the night - can easily carry in a jacket pocket. some folks go to the extent of carrying around a clear shield with them and actually switch them out based on the situation. that's another option but much more of an inconvenience especially if the helmet you have isn't the fancy quick-change type, or if you don't have a bag or something to carry the additional shield.
also you may want to check on the laws in your area as it may be illegal to wear a tinted shield at night. so may not want to risk getting pulled over for that.
good luck! i do like the look of the bell bullitts, and may consider picking one up to add to my helmet collection.