This is for California drivers.
As long as I drive the truck without any load on/in the bed I will be fine, but as soon as I put anything on the bed...even a grocery bag. It becomes a commercial vehicle and requires a CDL and a "CA number" and if I load dirt or other commodity I need a CPUC number also. This is regardless of weight issues or 26,001 lbs.
Not exactly. By CHP / California rules, any built vehicle is a commercial vehicle. CHP officers and scales are all over the place. By their rules, a 1/2 ton with a service body or flat bed has to go through scale as it is a commercial vehicle. 50% of the scales understand that, the other 50% get [censored] that you are driving through! You'll notice most California scales say "No Pickups". A pickup is never considered a commercial vehicle. ( Hauling a trailer is a different story.) If it left the factory as a cab / chassis, that is a commercial vehicle. If it left with a pickup bed, it is not. Chevy doesn't build dump truck bodies, someone else does and adds it to a cab / chassis.
Then you have to to not only consider weight, but combined vehicle lengths, etc. Since I have a California CDL with Haz Mat endorsement, I can drive almost anything. I don't have the doubles endorsement. I don't worry too much about what vehicle I'm driving until it is a 26,001 or more. Then I have to do a daily inspection on the vehicle and fill out a drivers log ( although I have some exemptions there.) Every two years I need to renew my medical cert ( although, I recently start taking some BP pills and that put me on an annual recert.) Every four I need to retest on my Haz Mat.
As long as you follow the California BIT requirements, the CHP won't bug you. They just want to know that you have a safe vehicle on the road. Sometimes easier to do with fleets than it is to do with individuals.