It depends on the property and your market, but I would start social media profiles for the property or your brand if you plan on expanding. 

I know legal ownership and beneficiaries can increase that coverage in a number of different combinations, but are there ways you can think of to expand coverage specifically with the solo 401k's?

There are so many lost opportunities relying on assumptions that aren't accurate and easily verified.

We self-managed 20 properties while working 2 full time corporate jobs pretty easily.  

You should be able to do that fairly easily.

In a place like SE Michigan, we are lucky in that prices are low enough that you can find deals in solid neighborhoods that easily return well.

And make sure to work with a realtor who is also an investor and can easily plug you in with their network of GCs, PMs, and lenders. 

Once you’ve got the hang of that you can easily repeat the process or go bigger.

Yes, we exist.You may want to consider working with your accountant remotely to expand your options.I would also recommend looking for a accountant willing to work with you throughout the year.

If it’s a smaller home that has a high occupancy already it may not be worth it, small homes (1-2 beds) that are priced and marketed well in the Denver metro can easily stay over 80% year round.