Our NTU 2013 Casita
SD 17 came with a removable wheel (you have to take it off when traveling, as it hangs down too low). I asked about it, on the Casita
Forum I think, and responses were universally, "Get a foot! You don't want a third pivot point and the danger of the trailer rolling unexpectedly!"
So I got a removable Curt Jack Foot from Amazon:
and that's what I use all the time. Some say the wheel is useful if you need to have the trailer pulled up onto a flatbed tow truck, so I keep it in my TV just in case. The jack foot works great.
For backing up, I bought a pair of magnetic telescoping yellow balls, like those in the photo below.
Ultra-Tow Magnetic Trailer Alignment Kit | Trailer Alignment| Northern Tool + Equipment
You put one on your hitch ball, and the other on the hitch and back up, keeping them in line. All my wife has to do is tell me how many inches distant I am. But if you first raise the trailer hitch so it hits the guide stem on your TV, you could manage it by yourself.