Self directed Roth IRA to fund your deals

Hi everyone, so I recently learned about self directed IRA and the many ways it can help you when structuring your deal. I just wanted to throw out a what if questions to see if I'm on the right track.

So here's the scenario, let's say I put a property under wholesale contract and I'm looking to make $10,000 off the contract. I have to put down an option fee of $1000. I want that $1000 to grow into the $10,000 that I'm looking to profit tax free. So I open up a Self Direct Roth IRA and wrote a check for $1000 to the property owner in the name of my Self Direct Roth IRA account.

Now here's where it gets tricky. According to the IRS, I do qualify to open a Roth IRA account, but have maxed out my yearly contribution on my employer 401K contribution already. So there's two question I have with this scenario:

1) Since I'm max out on my employer 401K contribution, can I still make contribution in the amount of $1000 after tax money out of my regular checking account to the Roth IRA account to fund my wholesale deal?

2) What are the reasons that I can't structure this "what if" deal this ways?