I don't think that's a good idea... Bacon grease is too fatty and you could end up with huge vet bills as a result of the pancreatitis he'd get.
The foods you mentioned aren't great... Good food is more expensive per bag, but you end up spending less on vet bills and you also feed significantly less too. I was a student until May last year and I never gave up the good kibble after doing the math.
Maybe you should try a fishy food? A lot of picky dogs like fishy foods.
Here are three:
Solid Gold Barking at the Moon
DVP Sweet potato and fish
Wellness Fish and Sweet Potato