Medium Duty, or Full size semi

Good morning ladies/gentlemen hope all is well. I wasn't too sure where to post a question like this so I apologize if its in the wrong spot.

So a little back story, I have a smaller single person welding business with shop and typical 1 ton dually mobile rig right now. However there is a chance we will be attaining some heavy construction customers which will require welding on excavators/crushers/dozers and that sort of thing which will require a different welder weighing in at almost 3000LBS, which will very quickly start putting me into 5500 territory once tools are factored in. So after speaking with my father inlaw whom also is in heavy construction he said to go with a medium duty or full size semi with a longer wheel base and a deck. Our plan is to put a hiab knuckle boom on it, remove fifth wheel plate and install a fully custom 16 or 18 foot skirted deck, Toolbox headache rack combo, gooseneck ball for our 35' flat bed gooseneck trailer etc. These customers will also require some travel generally 7 to 1300KM one way, having a truck with a decent size sleeper for projects like this would make an excellent " self contained " welding rig I feel being able to sleep on site for a few days while I do the job would save money on hotels, or like ive done before pull our 38 foot fifth wheel to jobs which adds another set of issues such as finding a spot to park it and unhook from welding rig. While I was possibly hoping to stay in medium duty truck territory the sleepers on those are so incredibly small such as the freightliner M2 with the 24" bunk in the extended cab that kind of seems like you'd have to be 100lbs soaking wet to sleep in something like that comfortably?. The Mack granite, and the kenworth T880 have nicer 38 and 40" sleepers. So after my long winded post, I guess my question is do you guys see any negatives of just going to a full size semi with a decent size flat top sleeper? While I know its a bit over kill as I am sure you know theirs something to be said for comfort at the end of a long day. I was concerned about Bobtail weights and traveling in winter etc. But I am thinking the deck fully outfitted we would be pushing about 10,000LBS over the drives, we'd be also looking at a more vocational style truck to get that extra height/bigger tires as there will be some gravel and "offroad" if you want to even call it that.

I kind of have a vision in my head of it being the ultimate welding rig... Also kicking around the idea of incorperating a stainless steel shower and RV toilet which would be placed inside the center of my toolbox/headache rack combo that you would access through an RV type door. Mount a fresh water and black tank under the deck etc.

Would likely be looking for the lower HP classes to save on fuel mileage a little bit... and either a 10 or 13spd... I suppose I would consider an automatic as well. Like I say not looking for a massive sleeper but that 38 to 40" range would be nice, I just feel the M2 would feel very cramped after a couple days?

The trucks ive been looking at so far are as follows

Kenworth T800 (love this truck dad drove one for many years! )
Western star 4900
Mack Granite
Freightliner M2-112 (still with smaller sleeper option)

 

I am actually in Canada so I imagine the rules are slightly different as to the states? I have a class 3 with air brakes right now, which allows me to drive a truck with 2 or 3 axles with air. After speaking to a professional driving school they said essentially I can drive anything up to a full blown semi. The one thing I cant do is pull a trailer with air brakes and of course cant exceed that 80,000LB rating. I asked about being able to pull our 21,000LB rated gooseneck trailer with that particular truck and they said their should be no issue as you are using a ball and not the fifth wheel hitch plate, and of course the trailer would have electric brakes. *Rubber duck, that is almost exactly what I am going for except with a sleeper!

 

after discussion we thought why not go for comfort as well as functionality, I think having the ability to sleep in your rig and not having to roll up everything on a multiple day job would be worth its weight in gold. Not saying you'd want to do it week in and week out. In all honesty this route is almost cheaper than purchasing a new 5500 dually at the price their going for these days. My 15 cummins limited dually MSRP at 93,000$ its just nuts! I think we would put this into a testing phase and purchase a truck with maybe 5 to 600,000KM and if it works out may look into upgrading in the future. The biggest thing is with a rig like that it would take me years to put on the KM that you guys that drive professionally do. I see myself only putting on maybe 20,000KM a year MAX with a truck like this.