Since I'm a new immigrant with no credit score, a DSCR with 30-35% down payment is my only option, so the 50K need to include that down payment alongside all other costs (closing, rehab, etc). 

How many mortgage lenders have you spoken with to get qualified and discuss allowable down payment options?

There are a few options(1)You can get connected with the larger wholesaler firms in the area (2) go through PCPAO site and skiptrace the buyers of similar properties as yours, (3) hunt down the agents involved in the sale of properties similar to yours or go to local REI meetings and pitch it to the investors there. 

If you find you are unable to raise the money for an all-cash purchase, switching gears to Fannie will only work if you have a LONG time to close in your PSA or have many extension options (which usually require more hard earnest money.)

Many good rental options in San Antonio/New Braunfels area.

Yes, this is an unsexy option and it doesn't offer the same tax benefits, but you would benefit from reduced volatility (so long as you don't obsess over fluctuating stock prices), greater liquidity, stronger management teams and superior assets.

The condo will limit the rental options to age restrictions. 

We want to know the best TRUST option, We have 3 rental units in North Carolina and each one of the units is on their own LLC.

If you do go the seller finance route, consider asking for a right of first refusal option in the event the seller ever decides to sell the note. 

Otherwise, I recommend option two, using a personal loan.