We've done 28 of 30 states in Mexico, plus Belize and into Guatemala in our 38 foot Monaco while towing a Honda CR-V. While dated, 99 Days to Panama.Com took their 30 footer down to, yes, Panama. Lastly, ExpeditionPortal.Com has plenty of in-progress adventures under their forum section. Your profile doesn't say what you are driving but you should be able to do it down to Panama at least.