There was a mobile windshield guy out of Glendive via Kalispell that used to serve eastern Montana. He came to my office parking area and did two of my windshields and I was perfectly happy with them.
One in the winter, he had to set up a portable shelter to do that. One in the summer, nothing special required.
It was an OEM windshield and his rates for the service were much lower than the local shops, which I have also used.
I would still use the service if it were still around. I don't know what happened to him?
I know where my sisters live they have mobile oil change, mobile windshields, mobile mechanics, mobile (house call) veterinarians and GP's (doctors). They all stay very busy and are doing well.
You might make a go doing oil, but it might take some time to build your clientele. Winter might be a bear.