That trip is quite doable on a Versys, since we did it in the fall of 2015, leaving from Edmonton early September and arriving in Lima in November. Then in the spring of 2016 we did the trip from Clearwater, BC to Inuvik and that entailed doing the Dempster highway which is all gravel or mud depending on the weather. We got both, gravel, and mud with snow. The group of bikes were a 2007 Versys, a KLR650, and a Vstrom 1000. Oddly enough, only the Versys and the Vstrom made it all the way, as the KLR crashed out in Mexico. Go figure.
This is the link to that trip.
Here are some of the things we did.
1) String a spare clutch cable alongside the original one, shrink tube the ends to keep out the incessant rain down there. Mine broke in Mexico, and was a 15 minute fix.
2) Carry spare gas if you wish, I did and got to use it once, oddly enough in the States. There are plenty of places to gas up down there.
3) Arrange to pick up a new rear tire in the USA just before you cross into Mexico and carry it with you until you need it. Ours came from Phoenix.
4) As mentioned before, definitely screen off your rad, there is plenty of debris down there with your rads name on it.
5) Carry enough tools to do most major repairs short of an engine failure, down there a tool selection is considered a screw driver and a monkey wrench.
6) Get one of those compact air compressors and a tire puncture kit, you will most likely need it.
7) Consider using motels rather than camping, it is really cheap away from the main thorough fares and you get to sample to local fare. We had absolutely no problems with Montezuma's revenge, but did insist on drinking only bottled water. Also saves a lot of space, not having to carry the camping gear.
8) Get all your vacinations up to date, probably about 8 or 10 of them, since most of those countries have different requirements.
9) Border crossings are a nightmare, budget a day for each crossing, unless you a fluent in Spanish, then half a day. Immigration and Customs are separate buildings (or maybe a van) that are not obvious to find. You will need multiple copies of your passport, ownership, vaccination records, plus individual copes of your temporary vehicle import certificate that you get at each border crossing.
10) If you want to make your trip interesting, stay away from the Trans America highway and use the small back roads instead. Believe me, down there is motorcycling heaven, you will not find roads like that in Canada or the USA. See the link for some of the better ones.
11) Another option for getting around the Darien gap to Cartegena is to book on a small sail boat that sails from Porto Bello in Panama on a five day cruise thru the islands, with reef stops for snorkeling, $1000 for you and your bike. Get a hold of Captain Jack's.
12) Get a good GPS loaded with maps of Central and South America. It will save your sanity, when you get lost in some town with no clue how to get back onto the main road. Also take a small lap top, or tablet, there is wifi almost everywhere, use it for email, local info, etc.
13) As mentioned before, the rain down there is incessant, depending on the time of the year. Take good rain gear. We eventually didn't even bother putting it on when the weather was warm, just get soaked, then let the wind dry you off.
14) Oil changes: Non of us changed oil on the Peru trip, about 20000km, just added as needed. Granted, we were using synthetic. Chains lasted all the way to Lima, but were basically scrap by that time.
There is probably more, but my brain is on strike right now.
One last piece of advice, take it for what its worth. Go.