I completely agree that flips must be completed fast to keep the cash mobile so it can generate yet more cash.

Other ways of using SDIRAs could be to invest in syndications, performing  or non-performing debt, precious metals, raw land, precious metals, mobile home parks, self-storage facilities and more. 

Karl's Mortgage Calculator - This is a downloadable app for your phone. 

I did try to set up a property management software for collections but as I live in a rural area received a TON of pushback from my tenants about sending money over an App they were not familiar with.

The app is user-friendly and integrates with popular CRMs, making it ideal for both beginners and experienced investors.

Can you share whick app you chose to use in the end?

I own a unique mobile home park in South Carolina that's relatively small (5 acres) comprised of 12 lots (I own 8 of the homes while the other 4 are owner-occupied and charged lot rent) along with a house (3 units). 

Mobile county is more than 1%. some counties in Ohio as high as 2%+.

Personally, I've bought older homes since I invest in mobile homes myself.

They had no interest in the mobile home; they just wanted the property so another family member could build a home on it.