Started researching MDTs, now looking at HDTs with a conversion. I am trying to understand this. In WA, am I to understand that I can have a HDT conversion "RV" as a private coach/not for hire...tow another trailer, say with my personal vehicle, and as long as the trailer is less than 10,001 lbs, I would not need a CDL.

However, if I choose to drive a MDT or HDT and tack on a TETON 39' trailer 10,001 t0 20,000 lbs., then I am going to need a Class B CDL because the trailer exceeds 10,001 lbs....

Sounds like the HDT conversion with the lighter/smaller trailer in tow is the way to go.....not to mention the length restrictions for combos.

Hey there Snowman8
I am new here, this is my first post. I live in Washington State and I am
well versed in this. I have a 97 Freightliner Classic. I have not started
a conversion but wanted to be able to drive the truck.

The governing body for anything relating to CDL's semi trucks, etc. is
The FMCSA Federal Motor Carrier Safety Admin. I thought it would be
smart to get their interpretation. In their rules 353.- and this is
a new addition to them.. If you own the truck, and your driving it
for your own use, you are excepted.

BUT, while traveling north on I-5, I pulled into the weigh station at Cottonwood CA.
You see, even though it may be for towing a travel trailer, the CHP expects you to
stop. It seems I was right on the FMCSA exception, but the State Of CA. has
a rule that superceeds this. I was told that A. if I could get the truck licensed
in WA as a motorhome, AND at least got a class B endorsement, they would'nt bother me anymore. Well, Dept. of Licensing in WA said " to be considered a motorhome, it needs toilet and/or
stove or oven as well as a bed. No problem... I thought!

Got stopped at the weigh station on I-90 last week. The officer was very nice but he decided that even with a toilet or stove of sorts, there is now way you could live in a semi truck.

Heres the wrap up...
1. Every Officer has interpreted all of this in 'THIER' view.
2. Every retiree has the right to drive a 50' long motorhome with no problem.
3. When it comes to a semi truck, no matter what we 'think' we converted it to
I had better have at least a Class B CDL with air brake endorsement.
I know this to be true as in July the State Of CA. gave me an OUT OF SERVICE ORDER
which meant I had to HIRE A DRIVER TO GET MY TRUCK BACK TO WA. they would not let me
leave the weigh station with my truck.. Thats not a good feeling.

Hope any or all of this has helped.
Blackie D.

We ran into the same confusion at each scale house or Motor Carrier officer in site, within CA with our W900 and a 40' Toybox.
They will only acknowledge a motorhome conversion if the sleeper is a large box as a ICT sleeper, or a manufactured toter box on a large semi with all the ammenties you described to make it a livable home.
No longer the porta-pottie and LPG camp stove in the corner type thing. Has to be actually built into the structure of the enclosure and acceptable by the Highway Patrol and no longer the novice clerk at the DMV to get the thumbs up to change the title. If not already registered as such in CA, good luck getting the CHP to grant a registration change without a full blown conversion, they just dont want Class 8's pulling RV trailers with no CDL license.
The motor Carrier officers at Rainbow scales advised that they are trying to lobby to design a special endorsement for the larger Diesel Pushers in California, due to the GVWR ratings, lenghts of the newer coaches being driven by retiries..
The other thing they look for is the style and rating of the fifth wheel, a commercial hitch will not pass any longer, out of fear it can be possibly used as a comercial hauler at any time.
We gave up on the HDT and fifthwheel plan and had to purchase a full size Kenworth with a 39' motorhome conversion, and registered as a MH. Now, no problems with license and registrations/ insurance, etc.
For now anyway, it's California, so who knows when that will change for the worse again.