self employment and verification requirement?

Tax records?

 

Any receipts for the winnings?

 

Some companies will accept what you already have; tax records from 2016 and back. For 2017 a company may just want a notorized letter signed by a family member or friend stating what you were doing, during 2017.
You'll have to ask the company you plan to apply with what is required.
Some people havent' worked in years and were still hired.

 

DOT couldn't care less about your work history.
The rule is, you must account for your time and it doesn't matter if you worked or not, just as long as you can account for your time.
If you're already a CDL driver, you must account for the past 10 years.
If you're not a CDL driver yet, you must account for the past 3 years.
Trucking companies such as Prime or any others, can change this time frame to a longer period of time, but not shorten it.
Prime is one of the most picky about this, so maybe you should apply to some others.

 

Since you're hanging out in Las Vegas, check with Southwest Truck Driver Training. They have a school in North Las Vegas and will finance the tuition.

 

The purpose was to track your activities as a person working under dot rules. I have been up and down on the self-employed and semi-retired so I just put down self-employed on apps and they just ask what I did.

Oh by the way tax returns are not legal documents for employment confirmation.