The main reason carpet cleaners are looking for portables that they can run from their truck, is cost. They imagine that if only they had just a little more power, they could compete with a truck mount at maybe half the cost. Most of the time, they are deceiving themselves.
Think about what you really need. First, you need a machine that has enough vacuum power to run a 150ft. hose, a pump that can give you good pressure at that distance, you need an auto fill/dump system, some type of heater, (probably propane) a generator (6000-8000 watts), fuel tanks, (gas and propane) and all of the extra hoses you need. You will also be limited to only a 150 feet unless you use a vac booster which needs more electric power.
Now, if you just want a powerful portable to go where your truck mount can't go, you need a machine with 2 power cords, 2-powerful vac motors (preferably in parallel) can be 2-13.5 amp 3 stage or the newer 6.6 or 8.4 vac motors, a pump than can give you at least 300 psi at 1.5 gpm (4-flow). You can add auto fill/pump out if you wish but if you are only using it for suites, it's a bit of a waste. The machine should have 2 inch plumbing through out. This will enable you to add extra hose when necessary.
I have many highrise penthouses that I do, where instead of bringing the machine upstairs, I just add extra hose. The downfall of most machines like this is the size and weight. This is not a machine that will easily go up and down stairs, which is why you want a truck mount in the first place. The buildings where I use my portable all have elevators. Any portable, is not the right machine for cleaning houses. Yes, you can do it but it is a brutal job, which is why portables get such a bad rep. Small, single cord portables are great for upholstery cleaning and for the odd job where you just can't get in with your truck mount but they have very limited power.
It is easy to find enough power in a suite for even the larger portables but can be very difficult to find in some commercial settings, such as when cleaning apt. hallways and stairs. Often, there is only one power outlet in each hall. Most of the so called "Mega Portables" are a pita to use. You can get all the power you need from 2 15 amp circuits, if the machine is designed right. You will need to add a 3rd power cord to get heat. Instead of heat, maybe thing of adding something like a Rotovac 360i.
