So many decisions...

If you get your CDL now, and later turn 21 and want to go over the road....your local and "in-state" experience will be ignored by OTR companies.

Dohrn is a pretty good idea...they are ALWAYS looking for drivers, and would love to have you on the docks...probably train you and let you use their truck and trailer to test for Class A...and then run you in-state until you turn 21, then let you cross state lines. Once you have crossed state lines, your experience will be noted should you decide to apply for OTR elsewhere. (Paid to train, not pay to train)

Dohrn is not Union, but they pay fairly decent (I believe $15.50 to $16.50 an hour to start in Iowa....and yes all you freaking millionaires that is not bad for Iowa). They do NOT have pups...so you won't be hooking those up. Some of their equipment is older and beat up...and as a new guy, you will get what's left---but you're driving junk now, so it's an opportunity to get some combo experience.
I checked in with them back in 2010...so the hourly rate may have gone up; and I think they have some fairly decent benefits too. I didn't take that gig because something else popped up. But I wished I had...the Dohrn P&D guys were all starting between 5am. & 7am....and I took an LTL job that paid a little better, but got a crappy start time.

Just something to think about.