Before I bought a Harbor Freight cart to carry my silent partner star, balls, hopper, and other gear to the courts I used to stack all that stuff on the star and roll it approximately a quarter mile each way to my neighborhood courts. I never had a problem with the wheels on the star during the year and a half (probably 30 total trips) I did that but there was visible wear on the wheels and on the back of the machine itself from navigating curbs. The telescoping handle of the star is reasonably sturdy but I felt that eventually if I kept rolling the machine that far something would break so I bought my cart about a year ago and it has been great and was well worth the ~$45 I paid for it.
A cart may not be practical unless you have a pickup if you are driving your machine to the courts and even then it would likely be a pita. You might consider some type of folding cart with big wheels that would hold your machine. I thought about buying one of those before deciding on my cart and even tested that idea using a dolly I own to see how it would work.
When should you serve and volley in doubles? Only when you want to win.