I hope you are asking two separate unrelated questions, because there's no point in doing cost segregation for properties held inside your self-directed solo 401k, save for some very rare exceptions.Some of the Bigger Pockets experts who operate reputable costs segregation companies are @Bernard Reisz, @Yonah Weiss and @Julio GonzalezSome of the Bigger Pockets experts who offer Solo 401k administrator services are @Dmitriy Fomichenko, again @Bernard Reisz and @Brian EastmanReach out to them and see if they can help.

We don't allow any "deal-making" in the forums, which includes advertising your services or properties, looking for partners, etc.

Personally, I enjoy self-managing and screening is my favorite thing, so I'm not in the market for PM services, but a lot of my clients that I work with and other fellow investors would be interested in it.

Their customer service is great.

Pure client service.  

Securities and Investment Advisory Services offered through DFPG Investments, LLC.[1] Multnomah County Executive Rule No. 388, March 11, 2020[2]Marcus & Millichap, 2020 Multifamily North American Investment Forecast

You pay the contractor for their services and then keep all of the profits. 

To expand, @Ben Whittington, Dennis Doss and Anthony Geraci’s firms can prepare a customized set of loan docs for you in any state. 

It should be as easy as converting one conventional loan that cashflows well to a Debt Service Coverage Ratio loan or DSCR.

Out here we call it the MLS, Multiple Listing Service.