It is not clear if you are riding to Mexico. Or buying a bike in Mexico.
If you buy in Mexico: They sell the Brazilian made Hondas.
XR and XREs
https://www.honda.mx/motos/lineup
For plotting around in Mexico, I would select the XR 190L
A simple, cheap and robust bike.
https://www.honda.mx/motos/xr-190l
You do not need anything bigger.
( I have actually contact with a Honda dealer in Medellin/Colombia, for buying an XL190 i Colombia and head south. September ?)
70 mph ?? Then you are on the wrong road.
But if you think that you need a bigger bike. XRE 300 is the alternative for almost twice the price.
https://www.honda.mx/motos/xre300
Take a look at the CL150 Cargo. If you ride solo. Why have a dual seat. And not use the space for a luggage rack ?
But it takes some guts to go against the stream
A bike (in 125 cc version) that took Simon Gandolfi from Mexico to Ushuaia. And than up to New York.
https://www.amazon.com/Old-Men-Cant-...s%2C176&sr=8-6
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It is always much better to have something that is used also locally.
Easier with parts and maintenance.
And you do not scream "GRINGO". At least not with the bike.