A good riding buddy did this, storing his old R100GS BMW in Guadalajara, MX,
Merida, MX, and Antigua, Guatemala, during a year and a half of back and forth travel.
In each case he left his bike with riders met en route or found on-line on various forums, some just random encounters. All were ... FREE ... but my friend compensated them, brought gifts or took the whole family out to dinner or just left a wad of cash. Least one can do. He generally was gone for around 3 months each time.
In one case (on an earlier trip) he did have a bad experience with a guy who runs a bike rental outfit in Guatemala. In this case his bike was knocked over .. and left on it's side. (oil flooded air box and right side cylinder)
Also, his battery tender was unplugged ... so he had a to buy a new battery ($100 USD). This was the only time he was asked to pay for storage. It was also apparent that his bike had been RIDDEN while he was gone. No doubt rented out!
The owner of the rental place is a British guy "well known" in Antigua. Unlikely a Guatemalan would never do this sort of thing.
So, as always, you take your chances. But bad experiences are RARE. Use your best judgement, try to place the bike somewhere where it will not be in the way or moved and where it's secure. Cover it, disconnect battery.
Mexico has a 6 month limit on the TVIP. Not sure on Guatemala or rest of Cent. America at this point. I think Guat. is 3 months? My bud above over stayed his permit ... had to pay around $100 USD upon exiting Guatemala. But that was 5 years back.
I'm not familiar with current policies regards over staying TVIP. I would ask around on Mex/Cent.Am forums here and elsewhere to learn details on specific countries.
AFAIK, no C.A. country link your passport to your bike and your TVIP. I believe you can come/go independently of your bike. Some countries may link it, I think some S. American countries DO link to your passport currently. Good luck!
PS: Far as I understand, Cambria is no more. The California event has been moved to Mariposa, CA in the Sierra foothills. Man, it can get blisteringly HOT in Sept.