driving via Guatemala from the U.S. to Belize is a little out of the way.
Well, each time I was riding around Tuxtla Guttierez or San Christobal I saw a lot of cars carrying a second car and some of them I spottet again near the Western border some days later and they all say that it is more convenient for them. So maybe it's out of the way for you and your requirements? but not for others!
If you have to head towards Benque Viejo del Carmen I even suppose that there are ways shorter than all the way through Escarcega and Chetumal and I remember many times I had been stopped by Mexican police and had stops of more than one hour and been searched like a drugs dealer (maybe my car a 1984 Mercedes Benz Diesel was suspicious???) - on the way through Guatemala I have never been stopped.
Whenever I headed along the Pacific I felt the streets very much better, there was never a lot of traffic and the crossing of the border into Guatemala always very uncomplicated and quick and sometimes I even prefer the road through Tapachula, Guatemala City, Flores and take the Western border and to cross the Western border seemed always less complicated, with immigration and customs more friendly and things easy going and 5 minutes later I'll be home with my family.
There's a monthly truck coming to Belize from Texas and they usually come in through Guatemala and the Western border. Do you think they take this road because it is out of the way?
It's only out of the way as long as you limit yourself to your special limitations but a lot of people do not have those!
A gringo driving down fro the states through Mexico and Guatemala and carrying a package????
Once again a comment with very limited imagination. You quote and judge without knowing anything :-)
Can you imagine that I find a way to make the driver buy what I need so that he's completely save and will not have to take any risk and he'll be carrying this item to me and I'll even pay part of his gasoline - what's "no bueno" on this deal?