Avoid mixing relationships and business.

I did a mix of hard money loan and 0% business credit cards.

In Real Estate, TIME IS MONEY.Getting a rehab loan done quickly is worth paying an extra few points in order to be efficient as you will be able to expand your BRR business which would yield results greater than the increased cost of capital that hard money brings.In order to escape a scarcity mindset you need to understand that money is in theory unlimited, they print it.But can you print time?

This is a time consuming business.

Will the renting of ADU rise to the level of trade or business? 

Regarding the masterminds, I'm in two and they have been hugely impactful for my growth, both as an individual and my real estate/business growth. 

Don't quote me on that, but it's easy to look up the IRS regulations.I recently had a conversation with somebody else who is planning to start an STR business. 

Almost any business you look at has its own gurus and scammers.

Here are some financing options to consider:HELOC or Cash-Out Refi on Another Property – If you or your mom have equity elsewhere, this could be a more flexible and lower-interest option.Business Line of Credit – Since the property is in an LLC, you might qualify for a business LOC, which could cover construction costs.Private Money Lender – If you’re okay with 12-15% rates, a private lender could fund this as a short-term loan, especially if the guesthouse will generate strong income.Construction Loan – Some lenders offer short-term construction financing, which converts to a longer-term mortgage once completed.Seller/Partner Financing – Bringing in an investor or structuring a joint venture with someone willing to fund the build in exchange for a share of the income.Credit Card Stacking or Unsecured Business Loans – Riskier but could work if you need to bridge a gap until the unit starts cash flowing.Would love to hear more details—especially your timeline and expected rental income.

I normally advise that people start a business as a sole propeitor in their first year.If it is successful and something you want to continue, then have a conversation regarding entities.