Also, if anyone has a favorite Skip Tracing platform and reason why its their favorite, definitely would like to know more as we've used many! 

Not only is the demands of each buyer going to vary by market and submarket, but also asset by asset.My favorite example of this was an old season of Flip or Flip, where they bought a house in LA county, versus their standard stomping grounds of Orange County.  

Quote from @David Ramirez: Call remodeled comps in the area that has been bought and sold within a year Especially for this method, you can paste the addresses in propwire and look in the chain of title to see the last owner before it was sold after being fixed up.

.#6 Locust Lake Village - Pocono LakeLocust Lake Village quickly became one of our team’s favorite locations in the Poconos.

Cold calling is only one marketing method.  

I would consider doing vanilla long-term rentals, but I think I want to do the BRRRR method, as scaling will be a challenge for me without it, I feel.

But hey its money whether its a living is another matter For the future I am switching to the buy it off the market and put it on the MLS with a realtor method.

Case by case, one by one, I sold my least favorite smalls by owner as they became vacant while the market was good.  

You listed two but in broader terms financing (assumable, owner financed, sub to, fha, new 95% OO LTV that in most ways is superior to FHA, dscr, F/f conventional, NACA, VA, etc), value adds (development including ADU, upzoning, traditional rehab, sophisticated value adds that leverage localized rules, coop/tic, etc),  property types (residential, commercial residential, land, storage, MHP, industrial, office, camping, hotel/motel, etc), passive/active investment methods (GP, LP, REIT, nnn, self managed, pm, flipping, mineral right, lumber rights, etc), residential rent models (LTR, STR, MTR, rent by room, student housing, arbitrage, etc).  

Are there any practical methods for implementing usage-based billing without submetering?