Basically, no. That seam cannot be "smoothed" or filled.

The closest you could get would be to use a fibreglass front end, like those used in the IDRA/NHRA.

But if you were to do that, you'd lose all the crash protection that the stock bumper provides. And you'd have to find a way to re-mount your headlights.
And then you'd have to keep the whole mess from wobbling in place as you drive down the highway.
And you'd need a whole laundry list of excuses for the officers that would inevitably pull you over and cite you.

So in short, it ain't worth it.