I am planning to create an LLC with the Solo 401k trust as the member to provide liability protection when I purchase real estate and some separation of assets within the 401k. 

That's probably your best bet for the refinance.Otherwise, there are long-term asset-based lenders as well, but they're going to be a bit more expensive.

They then use these funds to invest into whatever asset they choose. 

As for missing expenses....management software, management (regardless of if you are self managing), office supplies are a few that pop into mind.

@Chris Pohlson get educated on commercial/mfam and financing associated with the asset class. there's more scale and the financing (debt and equity) can become easier. 

Note the the law sees it different (they see an single member LLC as a different entity and hence you get asset protection...if everything is set up right).However, the IRS disregards the single member LLC for tax purposes.

So your going to hear a lot of different strategies on here however you have to find what works best for you and master it.You will hear all the Millionaire Real Estate Gurus say the #1 most important asset to have in this industry is being able to find deals.In my opinion the fastest way is "Door Knocking" just simply ask the homeowner directly have they thought about or thinking about selling their house period.

I used to do thousands of them back in the day for banks, insurance companies, asset companies etc.Haven't done it in a long time.The experience I can mention is the person you are wanting a value from doing  a bunch of BPO's already or mainly selling properties and making a commission?

My girlfriend and I wanted to buy a single family to live in, but after some researching and some eye openers (thanks Rich Dad Poor Dad) I realized I wanted to start acquiring assets and start my way towards passive income.

Up until 1/1/18 you could also exchange business assets for business assets under some very strict guidelines.