Truck mounts are all well and good but you have to consider a few factors
1.durring winter does the customer want windows and doors open.
2.the security issue, if your working upstairs and the customers front door is open any one can just walk in off the street.
3.Accessability, not always easy to get right outside customers house..
4.The cost off a truck mount would mean an incrase in price to your customer, if your a competant cleaner a porty for domestic jobs should be adequate.
5.A decent porty, stand it in the hall and run extension hoses you can clean a whole house without moving the machine.
6.we do alot of commercial work where you are required to enter areas using a security swipe card, you wouldnt be able to use a tm in that enviroment as security is an issue.
A TM is a graet bit of kit but would cost 20,000 New for domestic jobs can you justify the cost against 3000 for a good porty, you wouldt use a sledge hammer to knock in a picture hook!
Yours
John