It is entirely up to you what to Bondo and what not to Bondo.
Personally I chose to Bondo the whole cheek area including the plates, in order to make it all seamless.
My Advice is to finish shaping your dome and the areas of the cheek that you do have Bondo'd, then take a break.
Come back to your helmet with a fresh eye and critically inspect your helmet.
If you are happy with it... go to paint prep, if you are not happy... go back to Bondo.
Also watching the Video I can tell why your Bucket dome seems so lumpy.
You started at the top and worked your way down, applying a thick looking patch after patch.
To be fair I would have made the same mistake except i happened to talk to my Father on the phone and mentioned Bondo.
As it turns out he used to do ALOT of bodywork with Bondo and gave me excellent advice.
The second most useful bit of advice he gave me was to start at the bottom of the dome, with a small "sausage" of Bondo on the spreader, then pull it up to the top.
Doing it this way allows for the Bondo to fill the Low-points in the Dome gradually, layer by layer, while scraping the Bondo off the High-points.
This means you end up only with the Bondo you need and little excess that needs to be sanded off.
It is a technique lifted straight from Bob Ross's The Joy of Painting... and it works even with Car Bodyfiller! The man was a rare genius.
Keep your head up and your heart high, you will make this an outstanding bucket!