I'm not sure how fast you want to scale, but I see that as a feasible alternative if you don't want to go through the process of either BRRRing or the fix and flip. 

If this isn't an attractive alternative to your business partner then you might consider changing the ownership structure or operating agreement as one of your options.

These self employed 2nd mtg's are typically based on alternative method of caluclation like profit and loss statements if you're self employed or the last 12 months of bank statement deposits using a formula to derive an income from these deposits (like 50% of all annual rolling 12 calendar month deposits X 50% /12 months = monthly income).

If managing the STR is no longer sustainable @Robbie Shiver, here are a few alternative options to explore:Mid-Term Rentals: Consider marketing to travel nurses or corporate relocations for stays of 1-6 months.

@Matt Huber I think you know your answer already Direct real estate ownership should compensate you appropriately why else be in the alternative space.  

Is Guesty or Lodgify a good alternative? 

It's hard to place a price on something that has limited exposure in a market, with no comparable alternatives, but that doesn't make it worth more either.

I also recommend you discuss this with your tax advisor.There are many other alternative asset classes to invest SDIRA funds into. 

Alternatively, consider a cash-out refinance to access equity without triggering capital gains or explore a 1031 exchange to defer taxes by purchasing another investment property.This post does not create a CPA-Client relationship.

The strategy involves using the HELOC for a flip to generate fast cash, reinvesting profits into long-term rentals, or exploring alternative ventures like short-term rentals or partnerships.