How do I prove Income as a Day Trader?

I have very recently gone all in on day trading. My years long testing of the waters has proven its time to elevate this above a side hustle. With that being said does anyone have any suggestions or insight on how I would orient my life around it?

Should I create an LLC, is there a version of self-employment that matches this particular career, are there specific tax documents I should be filling out?

I am mostly concerned with down the road issues that would require me to prove income. for instance getting a car loan or mortgage situations. They ask for verifiable income which is usually verified through pay stubs. Since as a day trader I would be merely pulling money out of a trading account, what exactly should I be doing so in the event I need to prove income to an institution I can actually do so. I really wouldn't like to shoot myself in the foot long term simply because I failed to do something simple in the beginning.

Any help would be greatly appreciated, and if this is the wrong sub for this submission be kind and let me know where I should put it. I am not trying to pollute the sub, I am just genuinely asking for advice.