Welcome and first thing, listen to
@
BlackWorksInc
wherever he posts. He's a Toyota master tech who knows his stuff and is kind enough to share the wisdom here.
I can only speak to the '06 (I have an '07). Check for rust underneath as it's an issue with the 4th Gen (2003-2009) trucks. Also, you didn't mention whether it's a V8, which has the advantage of significantly higher tow capacity (7500 lbs. vs 5000 lbs. for the V6 IIRC) but comes with some of its own issues. The tow capacity difference is in how the hitch attaches; the V8 bolts to several frame points where the V6 hitch is only bolted to the rear crossmember.
Where are you in Atlanta? I'm north of Canton and work in Marietta. LMK if I can help with any other questions. There's also the group
GA 4Runners on Facebook that's very helpful.
I haven't yet used them myself but many of those FB group members rave about
Greer Auto Services in Woodstock. I mention that b/c once you have a specific truck in your sights, you might ask them what they would charge to look it over for you. They know Toyotas and IMO that would be a very wise investment given the age and mileage you're looking at.
Finally, here's an
article about towing a TT w/ a V6 4Runner. That's also my plan someday so PM me if you'd like to discuss any specifics on towing, like adding airbags to the rear springs, only towing in 4 (not D, per the manual), and so on. I think the people in the article should consider airbags based on the rear squat in some of their pics.
Good luck and let us know what you end up with.