Hi Lets start by saying I live in Maryland 30 years now. Retired from state work. Next I have a home in Baltimore so my truck and trailer are licence here. Next I have a home in WVA off of 70
so I go to WVA and back to Baltimore once a month. Now my big garage is in WVA,so I trailer my car or truck at least 2 a month, and have NEVER stoped at the scales.
My truck is a 2015 dually my trailer is a 2017 vintage at 44 ft goose. Truck is 15,000 gwr trailer is 18,000 . I do have a Maryland class A licence. no medical card needed for A maryland. Now here the trick my trailer has FULL Living Quarters bath, shower,stove, sink and a queen bed, so In the eys of maryland it's a RV. I have never ben stopped I run the speed and do not drive like a crazy person.
My stuff is clean and taken care of but I do not stop at the scales. You do not see RV in the scales, Motorhomes are well over 10,000 gvw and a lot with a trailer. Now when the truck and trailer do not match up they may be a problem but the might be a nother reason that your friend was stoped. Please rember that a CDL is commercial that neans that you get paid to haul somthing.
Now the big thing is a race team that wins prize money at a track or has a sponser can be commercial. If you are going to a show you pay to enter your car that is not commercial.We can so far
as to look at last year tax forms. One thing that will get you stopped in Maryland is if you have Example Maryland tags on truck and Maine tags on trailer.
One last thing to remember is 65 ft overall. Most big motorhomes and a short trailer will be ok Example 40 ft motorhome 24ft trailer = 64 ft but you have 4 ft of toung so to long.