Congrats, we took 4 years to drive the Americas. We'd be more than happy to answer any specific questions you may have or to point you to someone we know. Personally, we wouldn't caravan the entire way but more of hooking up with road friends to run certain sections together. There are lots of people running the Pan-American so making new friends is rather easy. Join the Pan-American Travelers Association group on FB but I must warn you that many veterans have left the group after becoming frustrated by the armchair know-it-alls. There are still some great experienced members, it might take a little work to sort through who knows what they are talking about and well...the others. Install iOverlander on your phone and familiarize yourself with all the different categories. It is the single best tool and includes border crossing information etc.. I can tell you that interest in the Pan-Am is on the upswing.
The best advice we can give is...it's a marathon and not a sprint. Do not focus on reaching an end point, it is much more about living in the moment. There will be times you will think you need to press on over staying with the group you are with, if you do press on it will become one of your biggest regrets. There are always more beautiful places to visit and reaching some arbitrary point is not the satisfaction any of us thinks it is. It doesn't matter if you make it the entire way and everyone's trip is different. A friend of ours once penned, in regards to multi country overlanding, "you will make life long friends that you may never see again in your lifetime." That, sums up the true experience.