I sometimes think these posts are just bait for some of us so, I'll bite
I'll preface my 2cents with background that as a kid in the Southwest, my parents carted us all about Mexico in an old Pontiac staion wagon, I've traveled extenisvely worldwide my whole life including time in Guatemala and Costa Rica in a 4wd.
That part of the world and the people you meet are awesome, yet Central America was never really what we romanticize it to be, and it dam sure isn't anymore. Traveling to well policed areas in relatively stable, gringo friendly counties like Costa Rica, Belize and Honduras is far different than weeks on the raw highways with a $50,000 travel rig. Please embark on this adventure with a realistic expectation and plan for all contingencies, many that never even enter your mind pulling an RV through US or Canada.
Everyone has stories of bandits, bribes, scams, attacks, and arrests. In recent decades nearly all these countries have, or are well on their way, to socialista regimes or worse. Politics are corrupt, dangerous and complicated with various resistance groups, criminal gangs, military, cartels and now foreign influences like China, Iran and Al-qaeda. If you get into any kinda legal trouble you are absolutely on your own
with little idea of who are the good guys and who are the bad guys. Line up as honest an attorney as you can find in each country you plan to pass through in advance.
As an American you are a target at best, an enemy at worst. You need cash for bribes, bail and emergencies - and having cash makes you an even bigger target.
It is my opinion that anyone putting themselves in this kind of dangerous travel situation has a responsibility to defend themselves, be armed, have weapon training for self defense in tight quarters and know when not to use it. Problem is that having quality semi-automatic weapons makes you even a bigger target for bandits (uniformed and not), and can get you in hot water at border crossings including re-entry to US. Heck, my travel plans in the US put priority on concealed carry states.
Your trip sounds like a true adventure I'd not rule out myself but I'd likely ship the rig, or just the Airstream to where I want to spend the most time - like maybe Costa Rica where I can buy or import a 9mm to tuck under the seat and a 12gauge to stash in the trailer.
Guns Of Latin America