Late to this discussion, but as a guy whose first run in a semi was in 1975, and who has run pretty much everything except reefer and in every state except Alaska, my advice is:
GET A TRAILER.
WITH ELECTRIC BRAKES.
And maybe a 1-ton or better dually pickup to tow it. If you have your choice, go Diesel, you can find older ones at good prices. But if you don't have the budget, your 3/4-ton Sub should work okay, I've pulled up to vehicle capacity trailers behind my 3/4-ton Diesel Sub with no complaints.
The trailer makes a big difference -- your less-than-wonderful experiences with rental trailers are because they use surge brakes. A good controller in the tow vehicle and electric brakes on the trailer will be a world of difference.
Why a trailer instead of the truck? First, think about what you want to do. You want to put a heavy load on this, and go blasting down the highway with it.
The problem is that highways are not flat and straight, so every curve, dip, bump and pothole will affect the vehicle, and the load on the vehicle. The closer that load (and center of gravity) is to the ground, the less the total effect will be on the whole combination. I've seen flatbed trucks on their sides, but can't think of a single time that I saw a low flatbed trailer like that.
Second, think about how you will load and unload. Low is easier, which is another reason to go for the car hauler. Stick a cheap winch on the front and pull the tractor up (BACKWARD -- I could tell you stories) by the tool mount, and you're ready to go.
Third, compare the registration costs of a trailer to those of any motor vehicle.
Fourth, consider that trailers are largely problem-free. Good tires, good lights and well-lubed bearings are pretty much all you need.
Fifth, even below CDL weight limit, your business-class truck has to put into every scale, while the Sub or dually towing a trailer cruises right past. Nothing good ever happens in scales. Scales are populated by people who are being PAID to find reasons that your truck should not be on the road, and most of them are very good at the job. Consider the difference in maintenance levels between the truck that averages 600 miles a day and yours, doing 6000 miles a year -- and they still find plenty wrong with the professionals. You would be meat on the table!
Sixth, let's say you're 500 miles from home and the engine gulps a valve. With the business-class, that means a big-rig tow to a big-cost repair shop. With the Sub or dually, that means a car tow to a car shop. If the problem, is serious, you get a ride home, pick up another tow vehicle, come back for the trailer, drag the tractor home, then take that same trailer back for the Suburban (depending on the trailer, maybe even for the dually).
The bottom line is that the simpler the solution, the better the solution.