And right now the bigger cabins are not a good cash flow play but might be a great equity play when you look back in two to three years.  

You can only play games for so long.Chances are your next door neighbor is an IRS agent and turns you in when your tenants blocks their drive or some other random event disturbing your IRS neighbor.ADU catches fire and your insurance won't cover you, because it was an illegal and unpermitted structure.The city inspector told the last guy not to build or rent it, and is now pissed and wants to make an example of you and just red tags the whole property and no one can occupy for the next 1-2-3 years while you wait for a hearing.Then when you get the hearing, "staff" recommends you tear the whole structure down, and if you still want an ADU, you can apply for a permit and rebuild it.Your tenant quits paying rent and won't move out and you can't evict them, because there is no valid lease and they're just your "roommate".Probably a dozen other bad things can happen to you when you do stuff like this. 

So things like, xbox/playstation ping pong for the kids maybe a turf strip to play some putt-putt for the adults etc...

The play book as you described is an old one when it comes to marketing themselves nothing different than what the how to trainer do.

Final thoughtsSo its been a journey, I am contemplating going full-time in entrepreneurship as this is my second successful business, my end goal in life is to have the option to retire by 35 haha so I want to do everything in my power now for future me.

That said, utilities that aren't directly attributed to a unit can be a pain in the neck because everyone is sure that the other unit(s) are using more power than they are.

You may just stumble into seller financing if play your cards right.

The power of rent growth.  

This plays into the affordability issues for tenants by allowing them to live in nicer neighborhoods for less money, yet I get monthly revenue comparable to short-term rentals.

This could be an awesome play..