I am, in no way, financially an expert at this, but what I have are several LLCs that I formed in a tax-friendly state. My accountant in that state is aware of exactly what I am doing, and he files my 'work-related expenses', as is legal. I'm an "entertainer" in the eyes of the IRS, with that particular LLC filing, so everything from hair, makeup, nails, travel, etc is getting deducted, which is perfectly legal. This also makes it so I have verifible income, so renting an apartment, buying property, etc, is much easier. The taxes I pay for that LLC are certainly not negligible, but I also set up a SEP-IRA retirement plan through that LLC and am making the max yearly contribution, ($53 k, which you are also not being taxed on, right now).
The rest of the income for this LLC is put into my investment account where about 50% is put in higher-risk investments(because I am young and can afford to take more risk), 30% in medium- low- risk investments, and the remainder is placed in a money market account which earns a higher interest rate than what your bank is giving you. I don't put everything through this LLC. I have other LLCs for other specific purposes, but I filter all cash through one of my LLCs. All of this is completely legal and safe because I am reporting and paying taxes on my income, it just so happens that my expenses and deductions make my taxes relatively very low, (it is not illegal to take advantage of every tax loophole your accountant is creative enough to legally use). My accountant is a former IRS auditor so he knows exactly what to do to avoid triggering IRS suspicion, while still abiding by legal tax laws. It's not illegal, is it sketchy as fuck? Possibly. Do corporations and lots of high net worth individuals take just as much advantage of the tax code as is possible? Certainly.
Also, I have.. several safety deposit boxes in different states with cash. It's illegal, I believe, to put US currency in a safety deposit box, but I could be wrong about that. None of my safety deposit boxes are tied to my legal name in any way, so they wouldn't be able to be seized if I was under investigation or being sued or whatever.
So, if you are making $10 k a month, I suggest setting up an LLC in a tax- friendly place, hiring an accountant in that state, putting the majority of your cash flow into that business account, keeping track of your expenses so they are being deducted, maxing out your SEP-IRA every year, and be honest with your accountant about what you're doing so they can do your taxes correctly and legally so as not to trigger red flags with IRS.
Good for you, that's a great monthly allowance, just be careful, as others have said, about triggering an alert with your bank for large deposits.
Btw, when you asked your SD about how to properly and legally handle this cash flow, what did he say? He can not be completely idiotic and think he can just transfer $10k or hand you a sack of bills that you can't deposit without suspicion. If he has the means to give you $10k/month, then he has the means to help guide you with how to save and properly invest the money without making trouble for him or you.