However, most investors I talk to go thru the SFR property experience and then after really understanding its limitations like a second job especially at turnover time (lack of scale, time, hassle) and then see they can get even better returns w/experts and save their weekends for more enjoyable family activities will do the shift. 

Then, once you have the experience, it becomes easier to attract money and then scale your real estate business. 

Especially if you want to scale your business model at all.

Syndications only make 15-25% at best and more for high net worth investors who need to scale.

We'd like to scale and get to 3-5 properties a month. 

Is there another way to scale at a more accelerated pace?

Getting your first rental property taking a little time and getting the concept of what needs to be done and learning the ropes and then scaling down the road. 

The third party leasing companies are able to leverage economies of scale/ bulk buying power on equipment / vertical integration to drive costs down such that they can install solar cheaply enough that they will be making money on the system very quickly if not immediately (by selling the tax credits to banks/investors/tax equity funds and by selling energy back to the grid at a premium) .

We have a few rentals currently are trying to figure out the best way to scale that makes sense.

I am sure it could be and every property manager and some scaling up would agree.