Anyone doing trucking as a Side Job?

Get the CDL and all endorsements first. This way you'll be prepared.
Might find a part time cdl job for your days off through a temp agency.
First get the cdl as a backup plan/insurance plan in case you're laid off or lose the job. Do you work at or near an airport?

 

No on the part time, and no on going ahead with CDL school unless getting your own authority is a goal.

If you got your own authority later, the age of the CDL is what will affect insurance rates. Whether or not you've actually used it doesn't matter.

From what I've seen posted here, guys wanting to work with an unused CDL are worse off than new grads.

 

The airline catering companies might have something for part time work. Some of those jobs are CDL Class-B and CDL Class-A. There's probably 4 of those companies in your area.
Go for the Class-A because it's good for Class-A and Class-B.

 

Driver Staffing/Leasing companies, what other industries call temp agencies have part-time work. Some customers have part-time yard truck work. I worked for a company that used a lot of temp drivers. The issue is temp agencies for CDL drivers back then wated 1-2 years CDL experience before thy would put you on the list so they knew you were competent enough to be sent to almost any customer. Back then they wanted drivers without an automatic transmission restriction so you could work for any customer. Many CDL schools almost have no way to give you training on manual transmissions and 90% of the industry is using automatic transmissions. So you are most hireable if you have CDL-A, all endorsements, no auto restriction, and 1-2 years experience.

Also, having an unused or very lightly used CDL for a year or two isn't real backup insurance since a stale CDL is probably going to require some sort of refresher course to be useful. Insurance companies make the decisions in trucking and they do not like 1 year or more away from trucking. They can hire newbies with no experience who just got out of school but they don't like someone with no CDL experience and 1 year since school/work. At 3 years away from school/work you are practically a newbie again, even with a dozen previous years of CDL experience, as I understand it.

THERE IS NO TRUCK DRIVER SHORTAGE, just some dishonest media stories by big companies wanting the govt to import lots of visa workers who will work more cheaply. CDL school is easy to start and complete on short notice, so if you always have enough money to pay for CDL school today, you essentially have what is needed to be working as a driver in the next 3 weeks. Not a lot of applicants fail at CDL school. Some do. Mostly what keeps you from working as a CDL driver is background problems (poor health, employment gaps, criminal, driving record, recent drug use). IMO, completing CDL school is almost a safe assumption unless you have some problem. Some few students are unable to back trailers properly or go around corners properly, but that is maybe in the 5% range, not 50+% range. You likely can assume you will complete CDL school 3 weeks after you start unless you are unusual. It's pretty high-stress job and pay is $50k for newbies. Pay also depends on what job and where. Rustbelt and very rural areas may have many more applicants than jobs.