I also don't know how day-to-day you are involved with your deals, but it sounds like what you are running into is a scaling problem (private lenders aside) - you can't do more deals because you don't have the bandwidth to do more. 

Quote from @Michael Lynch: People rarely talk about the amount of effort involved in operating a STR.Never sell a property unless you have a clear plan to reinvest the money into something that will perform better or move you closer to your goals.

Long-term rentals offer steadier income with less day-to-day involvement.

To get started, consider VA loans, which offer 0% down and no PMI, and house hacking, which involves buying a duplex or triplex and renting out the others.

The last time I did an insurance MTR it involved my work truck, an alternating current generator, 150 feet of extension cord, a sawzall, an appliance dolly, my 14 foot trailer, a house with fire damage and a $3000 Samsung French door fridge.Don't expect to make any money without doing any work.

Anything that involves a licensed architect or engineer providing a stamp is going to cost something, because they will review the person's work to determine if they're willing to bear the liability for that, and that takes man-hours.My previous firms always flat-out refused to stamp someone else's drawings because they had no idea whether any of it was on the level.

As a Contractor myself, on my New Constructions I use Lawson windows and I NEVER had a problem with these windows that involves quality, I’ve had problems with the other manufacturers that were mentioned above.

If they ask you to help, then you can get involved.

I have done this a few times myself and have a few basic recommendations:1) Make sure the seller owns the property free and clear and that it's very clear to both parties whether the arrangement involves a deed of trust or contract for deed2) If a balloon payment is involved, be sure to assess your ability to refinance and make that balloon payment in the future- optional extensions can help manage this risk3) Understand the tax implications if the interest rate is notably above or below market rates4) Get title insurance! 

There is a calculation that takes place and usually involves market based investments.