I looked for a while for a solution to this, but all the options I found had you inserting a large pill shaped piece in those huge gaps. I hated the look of that. I ended up buying a used Badlands grill off this forum and installing that.
I originally was planning on 33’s too, but I found these takeoffs on Craigslist and I took a chance. I think you might be disappointed with 33’s. I would have been. 35’s fit the truck so well and the height difference is negligible. Mine is a daily driver too.
I can’t speak to the MPG...