OHV sign question

I came across a OHV sign a while ago in Southern California that said no cross country travel. The trail had bikes and SXS icons, this may be a stupid question but. Can a truck access this as a fun trail for small whoops? I didn't go through the trail just in case it was off limits. I'd rather ask than ruin the trail.

 

https://ohv.parks.ca.gov/?page_id=26294

I would assume the "No Cross Country Travel" phrase is a fancy way of saying keep your *** on the trail.
As for the motorcycle/atv signs, I would guess that they are trying to restrict the size of the vehicles on the trail and keep trucks/jeeps from causing damage. But, I could be wrong.

 

You could be, but you aren't.

It used to be take a trail or make your own in most of the SoCal deserts. That's when you'd hear the phrase "There's nothing out there!". Now, after figuring out there IS something out there they have been pushing to stay on the established trails. Many trails are also restricted to types of vehicles that can use them.