I called a CPA for advice on it and was advised not to, and to just go ahead and when tax time comes, file as sole proprietor.

My current source of income is provided through travel nursing.

After that, my downpayment money is gone and I'd have to find another source (not sure a hard money lendor would lend to someone with very few properties under his belt.  

I haven't purchased any properties yet, but my biggest source on leads has come from building relationships with realtors and getting on their mailing lists.

Not to mention if your SD retirement account is the sole investor you must have enough funds for the entire project, all costs, and any potential overruns.

I recently decided to become an investor myself and gathered BiggerPockets is a great source to learn the nuances of the business from a buyer's perspective.

Has anyone in the DC area found craigslist an effective source of finding motivated sellers?

I have absolutely zero interest in flipping, and am looking solely at buy-and-hold with long-term sights... to that end, Strawberry Mansion (or at least parts of it) seemed like it might be viable.

If I were you, I would focus on sourcing deals in less risky ways. 

Only income from the 1099 source (not the W-2) can be used to make new contributions to the plan, with a maximum at $53K - of which you can elect to make $18K Roth.You cannot use retirement plans as collateral for your own personal real estate purchases.