Awesome that you've already taken a few steps to broaden your REI knowledge, please feel free to reach out if you want to pick my brain to see what I did and if it aligns with your goals.

You can take participant loans from the plan, you don't need the additional expense and administration of an LLC to have checkbook control, and there is a built in-Roth component.

First of all Id Like to Applaud You on the Design Work and Execution as Well, Good Job.When I Read & Seen this Project , You & Your Abilities / Goals I Feel Align Quite Similiarly With Mine, Though Im Not A Designer Or Architect , I Had An Art Scholarship & instead of using my Creativity on Paper Iv Always Chose and Felt it was More Fulfilling to Apply my Talents to Building.I Have Been in the construction industry/Profession Since I was 13 & im 33.

Ask questions and seek mentors I partnered with a local agent that specializes in REO’s and investments (it is very important to find an agent who aligns with your goals) Started looking at properties while running numbers through the BP calculators.

If a BP member is trying to sell you a SFH that doesn't align with your goals don't buy it.

@Craig GarrowA Solo 401k plan can have a Roth component that allows for new Roth contributions from your self-employment earnings.

It seems your PM is trying to maximize profits against you, rather than aligning your mutual long term goals.

Last, you said it was a mixed use, so there is a commercial component. 

PMs already don’t usually have their interests aligned with yours.

(in other words, it only addresses income component "b", below) .