Planing on riding from USA to Colombia.
Fined it hard to decide between KLR 2002 for 2000usd or 2013 one for 5000usd.
Both have similar modifications and add-ons.
My concerns are liability on the one hand and on the other hand if it will be possible to sell more expensive bike at the end? Maybe there is comfort of having old, less attention bike?
About the difference between 1st and 2nd generation I think it's minor though you might prove me wrong? Don't think I will do much rough off road.

Any thoughts?

The newer generation KLR are better (suspension, brakes) but not much in it. If your lucky previous owner of '02 may have done a few upgrades to brakes and suspension. A big PLUS. BOTH bikes need up grades anyway ... so go with the cheap and cheerful '02.

It will need at minimum:
Doohickey up grade, sub frame/rear rack bolts (stronger stainless ones),
suspension work would be NICE ... stock on '02 is pathetic, Better seat,
Thermo bob ... more ...

There are hundreds more things you can do but may not really need for such a short trip with selling it off in the plan at trips end. So really, sounds like you may only need to get 20K out of the bike. It should make it if it's in reasonable shape now.

It's hard to sell KLR's down there ... it takes time and a low price ... so another plus for the '02 and low initial cost of $2000. You can't lose.
(famous last words!)

Go through the old dog and start off with NICE FRESH OIL, filter, new tires,
new tubes and spares, NEW battery (no matter what!) and most important,
new chain and sprockets. X ring chain is BEST.

Make sure the '02 KLR is not leaking or burning HUGE amounts of oil. It's normal they burn some oil ... especially at higher mileages and if running highway over 65 mph.

If it's more than a 5 to 8 ounces every 1000 miles ... I might have 2nd thoughts. DO keep oil topped up but DO NOT overfill either. (really dumb thing lots of guys do)

ALL KLR"S use oil. Get used to it. (yes, new generation too!)

Good luck, write up a report, let us know how you do!