:welcome: to the site. I bought my 2001 4x4 last year with less than 55k miles in mint condition for under $10k. Since time is on your side, if you want a Sport Trac that meets the requirements you posted, don't settle for less. They're out there, but you'll have to search. I spent a couple months finding what I wanted.
Not to run you off, but I agree with the Escape/Mountaineer suggestions. You have a truck already and most likely don't need another four feet of bed space. If your wife likes the driving characteristics of the Explorer and the ride height, consider the Sport Trac. If she would be comfortable sitting a little lower and driving the less predictable front wheel drive, give more consideration to the Escape/Mountaineer. In other words, get her into both vehicles and let her decide which one is more comfortable and makes her feel safer.
For the money, I bet you can find a better equipped, better maintained, and lower mileage Escape than you can a Sport Trac. Escapes are also much more plentiful and will be easier to find. An Escape will most likely be my soon to be wife and I's next vehicle to add to the Sport Trac, Tahoe, and '69 Cougar (I'm working on converting her from a Chevy family).
If you do get a Sport Trac, don't be a stranger.