Where can I input nontaxable income such as VA disability payments received? I realize it is not required, but it's 50k that could boost the sales tax deduction.

You can add your nontaxable disability income in the Sales Tax Section using EasyGuide.  Follow the instructions below:

1. Open TuboTax
2. In the search box enter sales tax 
3. Select  Jump to sales tax in the results
4. At the Sales Tax and Income Tax screen, select Continue with Sales Tax
5. On the How do you want to enter your sales tax info? screen, select EasyGuide
6. Continue through the screens until you get to  the Nontaxable Income screen and select Yes
7. Enter  your nontaxable disability income and select Continue

TurboTax will choose the larger deduction.