Having driven an 18' Ford box van and towing an International Scout back in 1986 from Michigan to Belize...for a 1-year project. No boon docking and we hoteled it along the way this sounds iffy at best.
Much depends on one's ability to adapt to varied cultures and have a sound base in Spanish language skills.
And just be brazen!
As we were entering the outskirts of Veracruz I stopped at Pemex for fuel. We had been stopped at a stoped sign on a smaller side road for nearly 5 minutes when a break in traffic on the main highway appeared and I slowly pulled out to proceed south.
Almost immediately a Mexcian policeman pulled us over and attempted to give me a ticket AKA ask for a bribe, for Ahem NOT stopping a the same stop sign we were waiting at.
We had a fair amount of Belizean curretncy which he did not want and asked for my wallet for drivers license
etc. With only limited US $ he extracted about $50. I impulsively reached over and snatched the money away from his hand along with my wallet and told him I needed that to buy more gasoline in Mexico to continue south!
He seemed shocked at first then smiled and apologized and told us to follow him for a not well-known by-pass of Veracruz that would save some 20 miles and maybe an hour of travel. It seems he decided we were not typical Gringo tourists simply traipsing the countryside. This was after a short discussion of why we were going to Belize. "To study and protect birds" was our reply.
I trusted him and all went well and once we rejoined the main highway leading to BZE he waved and drove off.
As an aside after the Escapes safety course I am appalled by how overloaded we really were for this old Ford!
And our 1-year project was very dangerous ... as we stayed for 25+ years :-)
Let the adventure continue!