Do not lump CDL in with the others. It has its own rules that we will not go into because the rules start at 26,001 lbs. So no matter what you do not need a CDL.
Total weight has its own rules also but we will get to that later.
All the other rules; log book, insurance, physical exam, dot number, ect....start at 10,001 lbs for most trucks unless you are dealing with passengers or hazmat.
The out you MAY have is listed under rule §390.3(f)(3). This is a exemption from the rules for The occasional transportation of personal property by individuals not for compensation nor in the furtherance of a commercial enterprise.
This gets very sticky because some try to read what they want to hear into the rule. I am a farmer so the rules do not apply because I am not a commercial truck line. This is not true and the rules do apply because a farm is a bussiness.
SO.... Are you a bussiness???????
Now lets deal with weight.
Gross combined weight means everything. Truck; trailer; load; driver; empty coke bottle in the bed of truck. You have to worry about weight even if you are not commercial. Anyone can get a weight ticket even though most non commercial trucks are not even inspected.
If you are close yo not only should weigh the total amount you should weigh each axle. Most places like CAT scales will do this for you if you park on the scale correctly because it is not just one big scale. It is really three scales that weigh each axle seperate.
The reason for this is you can be under gross but still be overweight by having to much on one axle. Your truck plate should also tell you what is the max for each axle and you can figure the trailer by your axle weight ratings. Some states like Ga even separate duel axles but this is usually not a problem unless you have a broken spring or such.