Re: tongue weight
Couple of mistatements here about CDLs.
A CDL is required when the total rig is placarded at 26,001 pounds or more. Whether or not a person must have a CDL to drive the rig has nothing to do with what type of brakes are in the vehicle. If the rig is placarded at the specified weight or higher, but the trailer is placarded at less than 10,001 pounds, a Class B CDL is required. If the trailer is placarded at 10,001 pounds or more, a Class A is required and the rig is considered to be a tractor trailer. There are some situations where a rig at less than 26,001 requires a CDL (Class C) but, for the purposes of this discussion, the details aren't important. Notice that in all discussions of weight, I used the term "placarded." It doesn't matter what you have "on" (as in, load) the truck/trailer - if the sticker in the door, or a template on the trailer gives a weight to meet the standards, you must comply. Notice. also, that I am using the term "rig." If the truck is placarded at 19,000 pounds and the trailer at 15,000, you are now at 34,000 pounds, which is well beyond the 26,001 point, so you are in CDL territory if the rig is commercial.
The issue of brakes refers to airbrakes, for which a person's CDL will be restricted if he/she has not passed the air brake test. Other permissions in regard to a CDL are refered to as "endorsements" but have to do with hazmat, double trailers, etc. In everyday language, people tend to use the term "endorsement" in regard to the airbrake issue, but that isn't technically correct so some understanding of it is important.
If no one is paying you to drive the rig, ie: it is your personal vehicle, you can usually obtain a proper state license (Class E or F) to operate the rig legally. You also may by-pass weigh stations.
PS: Read bjcsc's post too - he is correct and I absolutely agree with his caution to read state rules.
CDLs are federally issued licenses which are administered by the driver's home state. Class D,E,F, etc. are state licenses. Individual states tend to have locally mandated rules and some of them are very obscure. For example, in the state of Louisiana, a paid driver operating a straight truck placarded at 25,500 (a common rental truck weight) would be thought to be able to drive it on a Class D license with no medical, because medicals aren't usually required for non-CDL drivers. Louisiana, however passed a law, which was tacked on to an environmental bill that was not about driving, which requires the driver to carry the medical card if the placarded weight is over 20,000 pounds.