You need to do some more work on the discount and rebates. Both seem way low to me. See my deal check here.
For discounts, you want to be closer to 6% off and should be reaching as high as 10% off. It’s pretty easy to qualify for GM supplier pricing, so you can look into this option if the dealer won’t move off the current discount.
For rebates, you don’t list what you qualify but again seems way to low. No conquest? No loyalty? I think Costco members are still getting a discount. When I was shopping these I was around $2000 in rebates.
Ultimately I would suggest you look into a Sierra 1500 Denali instead. A supplier deal with reasonable rebates won’t be that much more then these Silverado and will be better equipped.
The base MF is set by GM but the dealer can markup the MF.