I don't think you're going to get a staggering discount on a used 2019 at this point. A quick search shows only one in my general area for around $54,000 with over twice the number of miles you're looking at. You could call your local bank or credit union and ask them what they would value the truck at to give you an idea.
This is by no means an exact science, but if you want to justify it to yourself, assume the value depreciates 9% as soon as its driven off the lot. Assume it depreciates by a total of 27% within the first 12 months, or 1.5% per month. Figure out how many months have passed since it was purchased, and do something like this.
$62,880 x 0.91 = $57,220.80 value on day #1
$62,880 x 0.015 = $943.20 value loss per month for the first 12 months
If it was purchased four months ago:
$57,220.80 real value on day #1 - (4 x $943.20 representing 4 months of straight line depreciation) =
$53,448.00 estimated value today
Use that as a starting point and apply dealer discounts and rebates to the $53,448.00. Add in the dealer fees, tax, tag, and title, and you have an offer.
Just my two cents.
- Daemlar