The way I see it, you can only improve 2 things for UPS ...
1) heavy INTL time ... the reason for my 1st post, and you can
possibly change that.
2) Military time ... not going to change that.
And FWIW ... you CAN get hired at UPS without either of them !!!
BUT ... you really sounded like you wanted to sail on the Whale ! And you gave a few reasons why now was a great time for you to do it.
If your corporate job is that cushy, and keeps you happy, then stay put. You are qualified for UPS right now.
It really is a matter of what you want to do tomorrow ...