but what outlaw would wear white instead of assigned black color
He was always shown to be a master of disguise. Seems dumb to select one where you stand out like a sore thumb. Sometimes he would enter town as an old prospector and drive an covered wagon. Where did he get the wagon, and what did he do with Silver?
Remember, he still had a steady income from his silver mine. All he had to do was visit it from time to time and collect some bags of ore. That could keep him going for months.
Want to go into town disguised as an old prospector? No problem! Just talk to a local farmer and rent his wagon for a day or two. Silver? Just leave him with Tonto back at the campsite.
You gotta think like a radio or TV writer to come up with this stuff!
It wouldn’t match the rest of his outfit, style-wise. Coordinating the two was probably one of Tonto’s responsibilities in John Byner’s banned sketch. 
Only the ranger’s hat was white. The rest of his outfit was blue. Sometimes black.
With that sporty red bandana tied around his neck!
In the original radio programs, they mentioned that he wore a mask, but the rest of his appearance was left to the listener’s imagination.
In the earliest novels, the cover art depicted in standard cowboy gear: brown leather vest and chaps, a shapeless brown 10-gallon hat, and sometimes a brightly colored plaid shirt.
The Republic serials (The Lone Ranger in 1938 and The Lone Ranger Rides Again in1939) gave him a more streamlined appearance. He did not wear chaps or a vest, and he wore a more compact Stetson hat. The immaculately blocked white Stetson now became iconic. His clothes were gray, the trousers slightly darker that the shirt. But since the films were black-and-white, you could imagine them in any color you wanted. Lobby posters sometimes showed him in blue trousers, sometimes brown. His shirt was sometimes red, sometimes green, sometimes tan. The clothes were made of heavy cloth with a rough surface texture. The costume designer may have been trying to suggest buckskin.
Book jackets and comic books in the 1940s usually depicted him in a red shirt, blue or black trousers, and sometimes a black vest.
When the TV series debuted in 1949, his costume on a black-and-white set was a light gray. In promotional materials in other media, light blue became the official color. They re-issued a lot of the novels, with the cover art re-painted to reflect the new color scheme.
In the matinee serials, he wore a two-piece mask. A black leather domino mask covered the top half of his face, and a black gauze veil obscured the bottom half of his face.
In the serials, his saddle and gunbelt were black leather, sewn together with white leather stitches. In the TV show, the stitching was black-on-black, but the edges were lined with rows of white metal studs. Slightly different materials, but similar visual motif.
Okay, he rents a wagon from a farmer. Fanwank the disguises themselves. Where does he keep them? All he ever has when riding normally is a thin blanket behind his saddle.
Okay, I’ll fanwank.
He owns the wagon. He has an assistant who drives the wagon to each town ahead of him. The disguises and any other equipment he needs are held in the wagon.
The assistant takes no direct part in the adventure so is never mentioned.
In some iterations he wore a ranger badge openly. Also the mask wasnt like outlaws, who generally wore a bandanna over their lower face.
Maybe he kept all his bedrolls, coffee pots, kettles, etc., stored in his silver mine, and retrieved them whenever he wanted to set up camp. Granted, that would somewhat limit his radius of action, but it also explains why all the small towns he visited looked exactly the same. 
Alternatively, he could have Tonto buy new stuff every time he went into town to get supplies, and then just leave it behind when it was time to move on. Hell, the man owned a silver mine, so he could afford to waste money now and then.
but the how could a Ranger make enough money to buy a mine, unless he was a miner before
He and his brother inherited it?
You are correct!!
“Who was that masked man?”
“I don’t know, but he left all his crap. How long do we have to wait until they invent Goodwill stores?”
Has anybody mentioned yet that the Lone Ranger is the Green Hornet’s great uncle? The Hornet’s dad (the Lone Ranger’s nephew) was a second sidekick along with Tonto for a while. The word “Lone” must have been a lot less definitive back in the day.
The “lone” came from his being the sole surviving member of a Texas Ranger posse that was ambushed by outlaws.
I had a copy of this book back in high school when I was taking a course on radio. It’s pretty comprehensive, and a revised edition is available as well.
The great radio heroes : Harmon, Jim : Free Download, Borrow, and Streaming : Internet Archive
I new a guy in High School (1968) who did an impression of Tonto caring for him after the ambush, telling him the others are all dead: “You only ranger. You Lone ranger.” I don’t know if it’s really quoting the pilot episode.