More than likely, this property would be an out-of-state purchase, perhaps a multi-family, depending on my options, and implementing a buy/hold strategy. 

You're a new investor ...they sensed this and you don't live onsite and are managing the property yourself ....and yes your tenants talked to each other.Now is the time to be firm and better late than never.Go over with the tenants the expectations as set forth in the lease as to when rent is due and what the penalties are for being implemented and be firm.One tenant will possibly try to "test you".... and if they do you need to follow the local laws regarding g eviction ...otherwise they will run all over you.

So my question is, if we implement a policy of let's say no more than 3 total people per unit because of the size, will I have to ask my inherited tenant to leave since she is month to month?  

I say try to organize what you can now (get your product on the market), then iterate and implement improvements from there.

As stated life is not fare but in business you make it fairer by implement ridged protocols.

I was thinking about implementing the subject to strategy just to obtain a property here.

Recently a number of guests have just stayed late, up to an hour, so I implemented a change to my house rules to charge them for every 15 minutes they stay past their check out time. 

You are going to learn more by implementing the process than anything else.The most important thing is understanding timing of a wholesaling transaction and writing the contract correctly.

For example, the W-2 income makes life easy when applying for new loans and implementing the BRRRR strategy.

We are implementing the "BRRR"  philosophy.