What are some areas that already exercise?

And you do need to exercise some caution.

You may argue that you held the property for rental use for two years before the tenant exercised their option to purchase., and, you argue that this qualifies for capital gains tax treatment.I would argue that your intent to sell (flip) never changed, and, that the lease purchase option was just a marketing vehicle to facilitate the sale which allowed your buyer time to get financing in place. 

My realtor has shown me a couple listings but pulling comps seems like an exercise in futility.Thanks in advance.

You can't exercise the due on sale clause against a surviving joint tenant.

Just don't borrow that money to have it sitting in your account - it's has to be exercised or it's just a waste.Ultimately and obviously, whatever you do and whatever strategy you're using, you must overestimate ALL expenses, and underestimate income, and then you need to still be clearing a decent cash flow.

How can I gently tell them I need to learn more about them first before showing it to them?

Granted not every tenant is like the other but, I have to exercise prudence and use wisdom to avert and mitigate any possible snafus.So, when renting to anyone I am very frank, not crass or rude, I am firm and what I perceive to be fair and when i'm not my property manger helps me.

Some of them need to be gently educated that you won't cry if they leave.And I wouldn't worry about her suing or anything, until/if/when that ever happened.  

You could play right into their hands, as they may call it a retaliatory eviction because they exercised their rights.