Truck Mount systems cost between $10,000-$25,000 not including the cost of the van or trailer.
Prochem makes an affordable box extractor for less than $2000. To add a heater would be a few hundred more.
Carrying a portable up stairs is awful.
You would be better using a small self contained.
Nobles makes a great one. So does Tennant.
For less money but still high quality you can go with NSS Stallion.
For a good economical unit EDIC makes a good product. You can get an EDIC from
www.cleanfreak.com for under a grand. I recomend paying a little more for a machine that holds more water. 5 gallon minimum capacity so you do not have to keep refilling.