I wrote the present owner of the Yuma Cabana, Casey J. Crawford, and received an email detailing all the history that he was able to find.
Here's an excerpt of his note: "...Built back in 1962, the office was actually an A-framed building, designed to look like a teepee (like our sign). Mr Patel removed the teepee office design and turned that building into a plain square box. Later, approximately 1995, we remodeled the office building to look like it does now. Our architect at the time recommended getting rid of the teepee sign because it "dated" the place, but we just couldn't do it --- we were nostalgic and like these kinds of things. The only change we've made to the sign was to change the "H" (in hotel) to a "M" (motel). It was originally called the Yuma Cabana Hotel (probably because of the larger rooms, interior hallways, balconies and superior construction?), but since most people now-a-days associate a Hotel with room service, restaurant, etc, it was decided to make this minor change.

I did make the acquaintance of one gentleman who used to work as a desk clerk a few years after the place was built. He said business was often very slow, even though it was on the Highway 80. Many nights, according to him, there wasn't even one customer. Things have changed since then as the town has grown. Over the years, many old motels have disappeared, been torn down --- with office buildings, restaurants or gas stations appearing in their place..." (Thanks, Casey.)