This is exactly why I get snippy with people who expect members here to give expert opinions based on simple descriptions.

Is it as simple as getting extra insurance?

I see you are looking at all sorts of strategies, from land to tax liens - to start I would suggest to keep it simple and basic.

My advice to you is to know more than your client does, simple as that.

For your first house hack, start simple and go from there.

In your example 100K loan and you fund 35K simple math.  

There are many more details to the transaction, but this is just a simple overview to show that YES your sdira can be leveraged more or at a higher leverage.

As @Joe Splitrock and others have mentioned, the simple answer is to go back to work in the same field you were working in, hopefully quickly and in a higher paid position, and continue building a strong employment history in your area of expertise. 

It can be as simple as maintaining the books, but it has to be something.One way you may be able to do this within one LLC is to setup each deal as a loan, rather than an equity partnership.

Home Depot sells laminate counters in up to 12 ft sections for approx $150 each that is very simple to install